Method and apparatus for processing image service

ABSTRACT

A method, performed by a digital device, for processing an image service according to the present document comprises the steps of: receiving image information; decoding a first image on the basis of the image information; processing the decoded first image to be displayed on a first area of a display screen; and processing a second image to be displayed on a second area of the display screen.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage filing under 35 U.S.C. 371 ofInternational Application No. PCT/KR2019/013067, filed on Oct. 4, 2019,which claims the benefit of U.S. Provisional Application No. 62/742,244filed on Oct. 5, 2018, the contents of which are all hereby incorporatedby reference herein in their entirety.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

This specification relates to a service processing method related tocontent using an image coding technique and, most particularly, to amethod and apparatus for processing image services based on imageinformation including an intra prediction information.

Related Art

The demands for high-resolution and high-quality images and video, suchas an ultra high definition (UHD) image and video of 4K or 8K or more,are recently increasing in various fields. As image and video databecome high resolution and high quality, the amount of information orthe number of bits that is relatively transmitted is increased comparedto the existing image and video data. Accordingly, if image data istransmitted using a medium, such as the existing wired or wirelesswideband line, or image and video data are stored using the existingstorage medium, transmission costs and storage costs are increased.

Furthermore, interests and demands for immersive media, such as virtualreality (VR), artificial reality (AR) content or a hologram, arerecently increasing. The broadcasting of an image and video having imagecharacteristics different from those of real images, such as gameimages, is increasing.

Accordingly, there is a need for a high-efficiency image and videocompression technology in order to effectively compress and transmit orstore and playback information of high-resolution and high-qualityimages and video having such various characteristics.

SUMMARY OF THE DISCLOSURE

A technical object of this specification is to provide a method andapparatus for processing image services that can decode and display amain image being derived based on received image information and/or asub-image being related to the main image.

Another technical object of this specification is to provide a methodand apparatus for enhancing image coding efficiency.

Yet another technical object of this specification is to provide amethod and apparatus for performing efficient intra prediction.

Yet another technical object of this specification is to provide amethod and apparatus for performing image coding that can derive an MPMlist for efficient intra prediction.

A further technical object of this specification is to provide a methodand apparatus for performing image coding that may reduce signalingoverhead by efficiently coding information on intra prediction.

According to an embodiment of this specification, an image serviceprocessing method performed by a digital device is provided. The methodmay include receiving image information, decoding a first image based onthe image information, processing the decoded first image so as todisplay the decoded first image in a first region on a display screen,and processing a second image so as to display the second image in asecond region on the display screen, and the step of decoding the firstimage may include obtaining at least one of Most Probable Mode (MPM)flag information, MPM index information, or remaining mode informationincluded in the image information, for a current block currently beingdecoded within the first image, configuring an MPM list by deriving MPMcandidates for the current block, deriving an intra prediction mode ofthe current block based on at least one of the MPM flag information, theMPM index information or the remaining mode information, and the MPMlist, generating prediction samples by performing prediction on thecurrent block based on the intra prediction mode, and generating areconstructed picture for the current block based on the predictionsamples, wherein, when the intra prediction mode for the current blockis not included among the MPM candidates within the MPM list based onthe MPM flag information, the intra prediction mode of the current blockmay be derived based on the remaining mode information, and wherein theremaining mode information may be coded based on a Truncated Binary (TB)binarization process.

According to another embodiment of this specification, a digital deviceperforming an image service processing method is provided. The digitaldevice may include a first decoder for receiving image information, anddecoding a first image based on the image information, a first rendererfor processing the decoded first image so as to display the decodedfirst image in a first region on a display screen, and a second rendererfor processing a second image so as to display the second image in asecond region on the display screen, and the first decoder may obtain atleast one of Most Probable Mode (MPM) flag information, MPM indexinformation, or remaining mode information included in the imageinformation, for a current block currently being decoded within thefirst image, configure an MPM list by deriving MPM candidates for thecurrent block, derive an intra prediction mode of the current blockbased on at least one of the MPM flag information, the MPM indexinformation or the remaining mode information, and the MPM list,generate prediction samples by performing prediction on the currentblock based on the intra prediction mode, and generate a reconstructedpicture for the current block based on the prediction samples, wherein,when the intra prediction mode for the current block is not includedamong the MPM candidates within the MPM list based on the MPM flaginformation, the intra prediction mode of the current block may bederived based on the remaining mode information, and wherein theremaining mode information may be coded based on a Truncated Binary (TB)binarization process.

According to this specification, a method for processing image servicesdisplaying a main image on image information received by a digitaldevice and a sub-image being related to the main image may be proposedherein. Thus, image services may be provided more efficiently to users.

According to this specification, an MPM list may be efficientlyconfigured while considering an increase in a number of intra predictionmodes. Additionally, a level of accuracy in the MPM list for indicatingan intra prediction of a current block may be enhanced, and an overallcoding efficiency may be enhanced.

According to this specification, by coding the information on an intraprediction mode based on a Truncated Binary (TB) code, signalingoverhead may be reduced, and the overall coding efficiency may beenhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates an example of a video/image codingsystem to which embodiments of this specification may be applied.

FIG. 2 is a schematic diagram illustrating a configuration of avideo/image encoding apparatus to which the embodiment(s) of the presentspecification may be applied.

FIG. 3 is a schematic diagram illustrating a configuration of avideo/image decoding apparatus to which the embodiment(s) of the presentspecification may be applied.

FIG. 4 illustrates an example of an image encoding method performed by avideo encoding apparatus.

FIG. 5 illustrates an example of a video coding method performed by adecoding apparatus.

FIG. 6 illustrates an example of an image encoding method based on anintra prediction, and FIG. 7 schematically illustrates an intrapredictor within the encoding apparatus.

FIG. 8 illustrates an example of a video coding method based on an intraprediction, and FIG. 9 schematically illustrates an intra predictorwithin the decoding apparatus.

FIG. 10 illustrates 65 directional intra prediction modes.

FIG. 11 illustrates neighboring blocks of a current block.

FIGS. 12 and 13 are flowcharts schematically illustrating a method ofconfiguring an MPM list for a current block.

FIG. 14 is a flowchart illustrating an embodiment of a method ofconfiguring an MPM list for a current block.

FIG. 15 is a flowchart broadly illustrating an encoding method that maybe performed by an encoding apparatus according to an embodiment of thisspecification.

FIG. 16 is a flowchart broadly illustrating a decoding method that maybe performed by a decoding apparatus according to an embodiment of thisspecification.

FIG. 17 illustrates an example of a content streaming system to whichembodiments disclosed in this specification may be applied.

FIG. 18 is a diagram schematically illustrating one example of a servicesystem including a digital device.

FIG. 19 is a block diagram illustrated for describing one embodiment ofa digital device.

FIG. 20 is a block diagram illustrated for describing another embodimentof a digital device.

FIG. 21 is a block diagram illustrating another embodiment of a digitaldevice.

FIG. 22 is a block diagram illustrating an embodiment of a specificconfiguration of the controller of FIG. 19 to FIG. 21.

FIG. 23 illustrates an example in which a screen of a digital devicesimultaneously displays a main image and a sub-image according to anembodiment.

FIG. 24 is a flowchart broadly illustrating an image service processingmethod that may be performed by a digital device according to anembodiment of this specification.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

This specification may be modified in various ways and may have variousembodiments, and specific embodiments will be illustrated in thedrawings and described in detail. However, this does not intend to limitthis specification to the specific embodiments. Terms commonly used inthis specification are used to describe a specific embodiment and is notused to limit the technical spirit of this specification. An expressionof the singular number includes plural expressions unless evidentlyexpressed otherwise in the context. A term, such as “include” or “have”in this specification, should be understood to indicate the existence ofa characteristic, number, step, operation, element, part, or acombination of them described in the specification and not to excludethe existence or the possibility of the addition of one or more othercharacteristics, numbers, steps, operations, elements, parts or acombination of them.

Meanwhile, elements in the drawings described in this specification areindependently illustrated for convenience of description related todifferent characteristic functions. This does not mean that each of theelements is implemented as separate hardware or separate software. Forexample, at least two of elements may be combined to form a singleelement, or a single element may be divided into a plurality ofelements. An embodiment in which elements are combined and/or separatedis also included in the scope of rights of this specification unless itdeviates from the essence of this specification.

Hereinafter, preferred embodiments of this specification are describedmore specifically with reference to the accompanying drawings.Hereinafter, in the drawings, the same reference numeral is used in thesame element, and a redundant description of the same element may beomitted.

This specification relates to video/image coding. For example, themethods/embodiments disclosed in this specification may be applied to amethod disclosed in the versatile video coding (VVC), the essentialvideo coding (EVC) standard, the AOMedia Video 1 (AV1) standard, the 2ndgeneration of audio video coding standard (AVS2), or the next generationvideo/image coding standard (e.g., H.267 or H.268, and so on).

This specification presents various embodiments of video/image coding,and the embodiments may be performed in combination with each otherunless otherwise mentioned.

In this specification, video may refer to a series of images over time.Picture generally refers to a unit representing one image in a specifictime zone, and a slice/tile is a unit constituting part of a picture incoding. The slice/tile may include one or more coding tree units (CTUs).One picture may consist of one or more slices/tiles. One picture mayconsist of one or more tile groups. One tile group may include one ormore tiles. A brick may represent a rectangular region of CTU rowswithin a tile in a picture. A tile may be partitioned into multiplebricks, each of which consisting of one or more CTU rows within thetile. A tile that is not partitioned into multiple bricks may be alsoreferred to as a brick. A brick scan is a specific sequential orderingof CTUs partitioning a picture in which the CTUs are orderedconsecutively in CTU raster scan in a brick, bricks within a tile areordered consecutively in a raster scan of the bricks of the tile, andtiles in a picture are ordered consecutively in a raster scan of thetiles of the picture. A tile is a rectangular region of CTUs within aparticular tile column and a particular tile row in a picture. The tilecolumn is a rectangular region of CTUs having a height equal to theheight of the picture and a width specified by syntax elements in thepicture parameter set. The tile row is a rectangular region of CTUshaving a height specified by syntax elements in the picture parameterset and a width equal to the width of the picture. A tile scan is aspecific sequential ordering of CTUs partitioning a picture in which theCTUs are ordered consecutively in CTU raster scan in a tile whereastiles in a picture are ordered consecutively in a raster scan of thetiles of the picture. A slice includes an integer number of bricks of apicture that may be exclusively contained in a single NAL unit. A slicemay consist of either a number of complete tiles or only a consecutivesequence of complete bricks of one tile. Tile groups and slices may beused interchangeably in this specification. For example, in thisspecification, a tile group/tile group header may be called aslice/slice header.

A pixel or a pel may mean a smallest unit constituting one picture (orimage). Also, ‘sample’ may be used as a term corresponding to a pixel. Asample may generally represent a pixel or a value of a pixel, and mayrepresent only a pixel/pixel value of a luma component or only apixel/pixel value of a chroma component.

A unit may represent a basic unit of image processing. The unit mayinclude at least one of a specific region of the picture and informationrelated to the region. One unit may include one luma block and twochroma (e.g., cb, cr) blocks. The unit may be used interchangeably withterms such as block or area in some cases. In a general case, an M×Nblock may include samples (or sample arrays) or a set (or array) oftransform coefficients of M columns and N rows.

In this specification, the term “/” and “,” should be interpreted toindicate “and/or.” For instance, the expression “A/B” may mean “A and/orB.” Further, “A, B” may mean “A and/or B.” Further, “A/B/C” may mean “atleast one of A, B, and/or C.” Also, “A/B/C” may mean “at least one of A,B, and/or C.”

Further, in the specification, the term “or” should be interpreted toindicate “and/or.” For instance, the expression “A or B” may comprise 1)only A, 2) only B, and/or 3) both A and B. In other words, the term “or”in this specification should be interpreted to indicate “additionally oralternatively.”

FIG. 1 schematically illustrates an example of a video/image codingsystem to which embodiments of this specification may be applied.

Referring to FIG. 1, a video/image coding system may include a firstdevice (a source device) and a second device (a receiving device). Thesource device may deliver encoded video/image information or data in theform of a file or streaming to the receiving device via a digitalstorage medium or network.

The source device may include a video source, an encoding apparatus, anda transmitter. The receiving device may include a receiver, a decodingapparatus, and a renderer. The encoding apparatus may be called avideo/image encoding apparatus, and the decoding apparatus may be calleda video/image decoding apparatus. The transmitter may be included in theencoding apparatus. The receiver may be included in the decodingapparatus. The renderer may include a display, and the display may beconfigured as a separate device or an external component.

The video source may acquire video/image through a process of capturing,synthesizing, or generating the video/image. The video source mayinclude a video/image capture device and/or a video/image generatingdevice. The video/image capture device may include, for example, one ormore cameras, video/image archives including previously capturedvideo/images, and the like. The video/image generating device mayinclude, for example, computers, tablets and smartphones, and may(electronically) generate video/images. For example, a virtualvideo/image may be generated through a computer or the like. In thiscase, the video/image capturing process may be replaced by a process ofgenerating related data.

The encoding apparatus may encode input video/image. The encodingapparatus may perform a series of procedures such as prediction,transform, and quantization for compression and coding efficiency. Theencoded data (encoded video/image information) may be output in the formof a bitstream.

The transmitter may transmit the encoded image/image information or dataoutput in the form of a bitstream to the receiver of the receivingdevice through a digital storage medium or a network in the form of afile or streaming. The digital storage medium may include variousstorage mediums such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, and thelike. The transmitter may include an element for generating a media filethrough a predetermined file format and may include an element fortransmission through a broadcast/communication network. The receiver mayreceive/extract the bitstream and transmit the received bitstream to thedecoding apparatus.

The decoding apparatus may decode the video/image by performing a seriesof procedures such as dequantization, inverse transform, and predictioncorresponding to the operation of the encoding apparatus.

The renderer may render the decoded video/image. The renderedvideo/image may be displayed through the display.

FIG. 2 is a schematic diagram illustrating a configuration of avideo/image encoding apparatus to which the embodiment(s) of the presentspecification may be applied. Hereinafter, the video encoding apparatusmay include an image encoding apparatus.

Referring to FIG. 2, the encoding apparatus (200) includes an imagepartitioner (210), a predictor (220), a residual processor (230), and anentropy encoder (240), an adder (250), a filter (260), and a memory(270). The predictor (220) may include an inter predictor (221) and anintra predictor (222). The residual processor (230) may include atransformer (232), a quantizer (233), a dequantizer (234), and aninverse transformer (235). The residual processor (230) may furtherinclude a subtractor (231). The adder (250) may be called areconstructor or a reconstructed block generator. The image partitioner(210), the predictor (220), the residual processor (230), the entropyencoder (240), the adder (250), and the filter (260) may be configuredby at least one hardware component (e.g., an encoder chipset orprocessor) according to an embodiment. In addition, the memory (270) mayinclude a decoded picture buffer (DPB) or may be configured by a digitalstorage medium. The hardware component may further include the memory(270) as an internal/external component.

The image partitioner (210) may partition an input image (or a pictureor a frame) input to the encoding apparatus (200) into one or moreprocessors. For example, the processor may be called a coding unit (CU).In this case, the coding unit may be recursively partitioned accordingto a quad-tree binary-tree ternary-tree (QTBTTT) structure from a codingtree unit (CTU) or a largest coding unit (LCU). For example, one codingunit may be partitioned into a plurality of coding units of a deeperdepth based on a quad tree structure, a binary tree structure, and/or aternary structure. In this case, for example, the quad tree structuremay be applied first and the binary tree structure and/or ternarystructure may be applied later. Alternatively, the binary tree structuremay be applied first. The coding procedure according to thisspecification may be performed based on the final coding unit that is nolonger partitioned. In this case, the largest coding unit may be used asthe final coding unit based on coding efficiency according to imagecharacteristics, or if necessary, the coding unit may be recursivelypartitioned into coding units of deeper depth and a coding unit havingan optimal size may be used as the final coding unit. Here, the codingprocedure may include a procedure of prediction, transform, andreconstruction, which will be described later. As another example, theprocessor may further include a prediction unit (PU) or a transform unit(TU). In this case, the prediction unit and the transform unit may besplit or partitioned from the aforementioned final coding unit. Theprediction unit may be a unit of sample prediction, and the transformunit may be a unit for deriving a transform coefficient and/or a unitfor deriving a residual signal from the transform coefficient.

The unit may be used interchangeably with terms such as block or area insome cases. In a general case, an M×N block may represent a set ofsamples or transform coefficients composed of M columns and N rows. Asample may generally represent a pixel or a value of a pixel, mayrepresent only a pixel/pixel value of a luma component or represent onlya pixel/pixel value of a chroma component. A sample may be used as aterm corresponding to one picture (or image) for a pixel or a pel.

In the encoding apparatus (200), a prediction signal (predicted block,prediction sample array) output from the inter predictor (221) or theintra predictor (222) is subtracted from an input image signal (originalblock, original sample array) to generate a residual signal residualblock, residual sample array), and the generated residual signal istransmitted to the transformer (232). In this case, as shown, a unit forsubtracting a prediction signal (predicted block, prediction samplearray) from the input image signal (original block, original samplearray) in the encoding apparatus (200) may be called a subtractor (231).The predictor may perform prediction on a block to be processed(hereinafter, referred to as a current block) and generate a predictedblock including prediction samples for the current block. The predictormay determine whether intra prediction or inter prediction is applied ona current block or CU basis. As described later in the description ofeach prediction mode, the predictor may generate various informationrelated to prediction, such as prediction mode information, and transmitthe generated information to the entropy encoder (240). The informationon the prediction may be encoded in the entropy encoder (240) and outputin the form of a bitstream.

The intra predictor (222) may predict the current block by referring tothe samples in the current picture. The referred samples may be locatedin the neighborhood of the current block or may be located apartaccording to the prediction mode. In the intra prediction, predictionmodes may include a plurality of non-directional modes and a pluralityof directional modes. The non-directional mode may include, for example,a DC mode and a planar mode. The directional mode may include, forexample, 33 directional prediction modes or 65 directional predictionmodes according to the degree of detail of the prediction direction.However, this is merely an example, more or less directional predictionmodes may be used depending on a setting. The intra predictor (222) maydetermine the prediction mode applied to the current block by using aprediction mode applied to a neighboring block.

The inter predictor (221) may derive a predicted block for the currentblock based on a reference block (reference sample array) specified by amotion vector on a reference picture. Here, in order to reduce theamount of motion information transmitted in the inter prediction mode,the motion information may be predicted in units of blocks, subblocks,or samples based on correlation of motion information between theneighboring block and the current block. The motion information mayinclude a motion vector and a reference picture index. The motioninformation may further include inter prediction direction (L0prediction, L1 prediction, Bi prediction, and so on) information. In thecase of inter prediction, the neighboring block may include a spatialneighboring block present in the current picture and a temporalneighboring block present in the reference picture. The referencepicture including the reference block and the reference pictureincluding the temporal neighboring block may be the same or different.The temporal neighboring block may be called a collocated referenceblock, a co-located CU (colCU), and the like, and the reference pictureincluding the temporal neighboring block may be called a collocatedpicture (colPic). For example, the inter predictor (221) may configure amotion information candidate list based on neighboring blocks andgenerate information indicating which candidate is used to derive amotion vector and/or a reference picture index of the current block.Inter prediction may be performed based on various prediction modes. Forexample, in the case of a skip mode and a merge mode, the interpredictor (221) may use motion information of the neighboring block asmotion information of the current block. In the skip mode, unlike themerge mode, the residual signal may not be transmitted. In the case ofthe motion vector prediction (MVP) mode, the motion vector of theneighboring block may be used as a motion vector predictor and themotion vector of the current block may be indicated by signaling amotion vector difference.

The predictor (220) may generate a prediction signal based on variousprediction methods described below. For example, the predictor may notonly apply intra prediction or inter prediction to predict one block butalso simultaneously apply both intra prediction and inter prediction.This may be called combined inter and intra prediction (CIIP). Inaddition, the predictor may be based on an intra block copy (IBC)prediction mode or a palette mode for prediction of a block. The IBCprediction mode or palette mode may be used for content image/videocoding of a game or the like, for example, screen content coding (SCC).The IBC basically performs prediction in the current picture but may beperformed similarly to inter prediction in that a reference block isderived in the current picture. That is, the IBC may use at least one ofthe inter prediction techniques described in this specification. Thepalette mode may be considered as an example of intra coding or intraprediction. When the palette mode is applied, a sample value within apicture may be signaled based on information on the palette table andthe palette index.

The prediction signal generated by the predictor (including the interpredictor (221) and/or the intra predictor (222)) may be used togenerate a reconstructed signal or to generate a residual signal. Thetransformer (232) may generate transform coefficients by applying atransform technique to the residual signal. For example, the transformtechnique may include at least one of a discrete cosine transform (DCT),a discrete sine transform (DST), a karhunen-loève transform (KLT), agraph-based transform (GBT), or a conditionally non-linear transform(CNT). Here, the GBT means transform obtained from a graph whenrelationship information between pixels is represented by the graph. TheCNT refers to transform generated based on a prediction signal generatedusing all previously reconstructed pixels. In addition, the transformprocess may be applied to square pixel blocks having the same size ormay be applied to blocks having a variable size rather than square.

The quantizer (233) may quantize the transform coefficients and transmitthem to the entropy encoder (240), and the entropy encoder (240) mayencode the quantized signal (information on the quantized transformcoefficients) and output a bitstream. The information on the quantizedtransform coefficients may be referred to as residual information. Thequantizer (233) may rearrange block type quantized transformcoefficients into a one-dimensional vector form based on a coefficientscanning order and generate information on the quantized transformcoefficients based on the quantized transform coefficients in theone-dimensional vector form. Information on transform coefficients maybe generated. The entropy encoder (240) may perform various encodingmethods such as, for example, exponential Golomb, context-adaptivevariable length coding (CAVLC), context-adaptive binary arithmeticcoding (CABAC), and the like. The entropy encoder (240) may encodeinformation necessary for video/image reconstruction other thanquantized transform coefficients (e.g., values of syntax elements, andso on) together or separately. Encoded information (e.g., encodedvideo/image information) may be transmitted or stored in units of NALs(network abstraction layer) in the form of a bitstream. The video/imageinformation may further include information on various parameter setssuch as an adaptation parameter set (APS), a picture parameter set(PPS), a sequence parameter set (SPS), or a video parameter set (VPS).In addition, the video/image information may further include generalconstraint information. In this specification, information and/or syntaxelements transmitted/signaled from the encoding apparatus to thedecoding apparatus may be included in video/picture information. Thevideo/image information may be encoded through the above-describedencoding procedure and included in the bitstream. The bitstream may betransmitted over a network or may be stored in a digital storage medium.The network may include a broadcasting network and/or a communicationnetwork, and the digital storage medium may include various storagemedia such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, and the like. Atransmitter (not shown) transmitting a signal output from the entropyencoder (240) and/or a storage unit (not shown) storing the signal maybe included as internal/external element of the encoding apparatus(200), and alternatively, the transmitter may be included in the entropyencoder (240).

The quantized transform coefficients output from the quantizer (233) maybe used to generate a prediction signal. For example, the residualsignal (residual block or residual samples) may be reconstructed byapplying dequantization and inverse transform to the quantized transformcoefficients through the dequantizer (234) and the inverse transformer(235). The adder (250) adds the reconstructed residual signal to theprediction signal output from the inter predictor (221) or the intrapredictor (222) to generate a reconstructed signal (reconstructedpicture, reconstructed block, reconstructed sample array). If there isno residual for the block to be processed, such as a case where the skipmode is applied, the predicted block may be used as the reconstructedblock. The adder (250) may be called a reconstructor or a reconstructedblock generator. The generated reconstructed signal may be used forintra prediction of a next block to be processed in the current pictureand may be used for inter prediction of a next picture through filteringas described below.

Meanwhile, luma mapping with chroma scaling (LMCS) may be applied duringpicture encoding and/or reconstruction.

The filter (260) may improve subjective/objective image quality byapplying filtering to the reconstructed signal. For example, the filter(260) may generate a modified reconstructed picture by applying variousfiltering methods to the reconstructed picture and store the modifiedreconstructed picture in the memory (270), specifically, a DPB of thememory (270). The various filtering methods may include, for example,deblocking filtering, a sample adaptive offset, an adaptive loop filter,a bilateral filter, and the like. The filter (260) may generate variousinformation related to the filtering and transmit the generatedinformation to the entropy encoder (240) as described later in thedescription of each filtering method. The information related to thefiltering may be encoded by the entropy encoder (240) and output in theform of a bitstream.

The modified reconstructed picture transmitted to the memory (270) maybe used as the reference picture in the inter predictor (221). When theinter prediction is applied through the encoding apparatus, predictionmismatch between the encoding apparatus (200) and the decoding apparatusmay be avoided and encoding efficiency may be improved.

The DPB of the memory (270) DPB may store the modified reconstructedpicture for use as a reference picture in the inter predictor (221). Thememory (270) may store the motion information of the block from whichthe motion information in the current picture is derived (or encoded)and/or the motion information of the blocks in the picture that havealready been reconstructed. The stored motion information may betransmitted to the inter predictor (221) and used as the motioninformation of the spatial neighboring block or the motion informationof the temporal neighboring block. The memory (270) may storereconstructed samples of reconstructed blocks in the current picture andmay transfer the reconstructed samples to the intra predictor (222).

FIG. 3 is a schematic diagram illustrating a configuration of avideo/image decoding apparatus to which the embodiment(s) of the presentspecification may be applied.

Referring to FIG. 3, the decoding apparatus (300) may include an entropydecoder (310), a residual processor (320), a predictor (330), an adder(340), a filter (350), a memory (360). The predictor (330) may includean inter predictor (331) and an intra predictor (332). The residualprocessor (320) may include a dequantizer (321) and an inversetransformer (321). The entropy decoder (310), the residual processor(320), the predictor (330), the adder (340), and the filter (350) may beconfigured by a hardware component (e.g., a decoder chipset or aprocessor) according to an embodiment. In addition, the memory (360) mayinclude a decoded picture buffer (DPB) or may be configured by a digitalstorage medium. The hardware component may further include the memory(360) as an internal/external component.

When a bitstream including video/image information is input, thedecoding apparatus (300) may reconstruct an image corresponding to aprocess in which the video/image information is processed in theencoding apparatus of FIG. 2. For example, the decoding apparatus (300)may derive units/blocks based on block partition related informationobtained from the bitstream. The decoding apparatus (300) may performdecoding using a processor applied in the encoding apparatus. Thus, theprocessor of decoding may be a coding unit, for example, and the codingunit may be partitioned according to a quad tree structure, binary treestructure and/or ternary tree structure from the coding tree unit or thelargest coding unit. One or more transform units may be derived from thecoding unit. The reconstructed image signal decoded and output throughthe decoding apparatus (300) may be reproduced through a reproducingapparatus.

The decoding apparatus (300) may receive a signal output from theencoding apparatus of FIG. 2 in the form of a bitstream, and thereceived signal may be decoded through the entropy decoder (310). Forexample, the entropy decoder (310) may parse the bitstream to deriveinformation (e.g., video/image information) necessary for imagereconstruction (or picture reconstruction). The video/image informationmay further include information on various parameter sets such as anadaptation parameter set (APS), a picture parameter set (PPS), asequence parameter set (SPS), or a video parameter set (VPS). Inaddition, the video/image information may further include generalconstraint information. The decoding apparatus may further decodepicture based on the information on the parameter set and/or the generalconstraint information. Signaled/received information and/or syntaxelements described later in this specification may be decoded may decodethe decoding procedure and obtained from the bitstream. For example, theentropy decoder (310) decodes the information in the bitstream based ona coding method such as exponential Golomb coding, CAVLC, or CABAC, andoutput syntax elements required for image reconstruction and quantizedvalues of transform coefficients for residual. More specifically, theCABAC entropy decoding method may receive a bin corresponding to eachsyntax element in the bitstream, determine a context model using adecoding target syntax element information, decoding information of adecoding target block or information of a symbol/bin decoded in aprevious stage, and perform an arithmetic decoding on the bin bypredicting a probability of occurrence of a bin according to thedetermined context model, and generate a symbol corresponding to thevalue of each syntax element. In this case, the CABAC entropy decodingmethod may update the context model by using the information of thedecoded symbol/bin for a context model of a next symbol/bin afterdetermining the context model. The information related to the predictionamong the information decoded by the entropy decoder (310) may beprovided to the predictor (the inter predictor (332) and the intrapredictor (331)), and the residual value on which the entropy decodingwas performed in the entropy decoder (310), that is, the quantizedtransform coefficients and related parameter information, may be inputto the residual processor (320). The residual processor (320) may derivethe residual signal (the residual block, the residual samples, theresidual sample array). In addition, information on filtering amonginformation decoded by the entropy decoder (310) may be provided to thefilter (350). Meanwhile, a receiver (not shown) for receiving a signaloutput from the encoding apparatus may be further configured as aninternal/external element of the decoding apparatus (300), or thereceiver may be a component of the entropy decoder (310). Meanwhile, thedecoding apparatus according to this specification may be referred to asa video/image/picture decoding apparatus, and the decoding apparatus maybe classified into an information decoder (video/image/pictureinformation decoder) and a sample decoder (video/image/picture sampledecoder). The information decoder may include the entropy decoder (310),and the sample decoder may include at least one of the dequantizer(321), the inverse transformer (322), the adder (340), the filter (350),the memory (360), the inter predictor (332), and the intra predictor(331).

The dequantizer (321) may dequantize the quantized transformcoefficients and output the transform coefficients. The dequantizer(321) may rearrange the quantized transform coefficients in the form ofa two-dimensional block form. In this case, the rearrangement may beperformed based on the coefficient scanning order performed in theencoding apparatus. The dequantizer (321) may perform dequantization onthe quantized transform coefficients by using a quantization parameter(e.g., quantization step size information) and obtain transformcoefficients.

The inverse transformer (322) inversely transforms the transformcoefficients to obtain a residual signal (residual block, residualsample array).

The predictor may perform prediction on the current block and generate apredicted block including prediction samples for the current block. Thepredictor may determine whether intra prediction or inter prediction isapplied to the current block based on the information on the predictionoutput from the entropy decoder (310) and may determine a specificintra/inter prediction mode.

The predictor (320) may generate a prediction signal based on variousprediction methods described below. For example, the predictor may notonly apply intra prediction or inter prediction to predict one block butalso simultaneously apply intra prediction and inter prediction. Thismay be called combined inter and intra prediction (CIIP). In addition,the predictor may be based on an intra block copy (IBC) prediction modeor a palette mode for prediction of a block. The IBC prediction mode orpalette mode may be used for content image/video coding of a game or thelike, for example, screen content coding (SCC). The IBC basicallyperforms prediction in the current picture but may be performedsimilarly to inter prediction in that a reference block is derived inthe current picture. That is, the IBC may use at least one of the interprediction techniques described in this specification. The palette modemay be considered as an example of intra coding or intra prediction.When the palette mode is applied, a sample value within a picture may besignaled based on information on the palette table and the paletteindex.

The intra predictor (331) may predict the current block by referring tothe samples in the current picture. The referenced samples may belocated in the neighborhood of the current block or may be located apartaccording to the prediction mode. In intra prediction, prediction modesmay include a plurality of non-directional modes and a plurality ofdirectional modes. The intra predictor (331) may determine theprediction mode applied to the current block by using the predictionmode applied to the neighboring block.

The inter predictor (332) may derive a predicted block for the currentblock based on a reference block (reference sample array) specified by amotion vector on a reference picture. In this case, in order to reducethe amount of motion information transmitted in the inter predictionmode, motion information may be predicted in units of blocks, subblocks,or samples based on correlation of motion information between theneighboring block and the current block. The motion information mayinclude a motion vector and a reference picture index. The motioninformation may further include inter prediction direction (L0prediction, L1 prediction, Bi prediction, and so on) information. In thecase of inter prediction, the neighboring block may include a spatialneighboring block present in the current picture and a temporalneighboring block present in the reference picture. For example, theinter predictor (332) may configure a motion information candidate listbased on neighboring blocks and derive a motion vector of the currentblock and/or a reference picture index based on the received candidateselection information. Inter prediction may be performed based onvarious prediction modes, and the information on the prediction mayinclude information indicating a mode of inter prediction for thecurrent block.

The adder (340) may generate a reconstructed signal (reconstructedpicture, reconstructed block, reconstructed sample array) by adding theobtained residual signal to the prediction signal (predicted block,predicted sample array) output from the predictor (including the interpredictor (332) and/or the intra predictor (331)). If there is noresidual for the block to be processed, such as when the skip mode isapplied, the predicted block may be used as the reconstructed block.

The adder (340) may be called reconstructor or a reconstructed blockgenerator. The generated reconstructed signal may be used for intraprediction of a next block to be processed in the current picture, maybe output through filtering as described below, or may be used for interprediction of a next picture.

Meanwhile, luma mapping with chroma scaling (LMCS) may be applied in thepicture decoding process.

The filter (350) may improve subjective/objective image quality byapplying filtering to the reconstructed signal. For example, the filter(350) may generate a modified reconstructed picture by applying variousfiltering methods to the reconstructed picture and store the modifiedreconstructed picture in the memory (360), specifically, a DPB of thememory (360). The various filtering methods may include, for example,deblocking filtering, a sample adaptive offset, an adaptive loop filter,a bilateral filter, and the like.

The (modified) reconstructed picture stored in the DPB of the memory(360) may be used as a reference picture in the inter predictor (332).The memory (360) may store the motion information of the block fromwhich the motion information in the current picture is derived (ordecoded) and/or the motion information of the blocks in the picture thathave already been reconstructed. The stored motion information may betransmitted to the inter predictor (332) so as to be utilized as themotion information of the spatial neighboring block or the motioninformation of the temporal neighboring block. The memory (360) maystore reconstructed samples of reconstructed blocks in the currentpicture and transfer the reconstructed samples to the intra predictor(331).

In the present disclosure, the embodiments described in the filter(260), the inter predictor (221), and the intra predictor (222) of theencoding apparatus (200) may be the same as or respectively applied tocorrespond to the filter (350), the inter predictor (332), and the intrapredictor (331) of the decoding apparatus (300). The same may also applyto the unit (332) and the intra predictor (331).

As described above, in performing video coding, a prediction isperformed to enhance compression efficiency. A predicted block includingprediction samples for a current block, that is, a target coding block,can be generated through the prediction. In this case, the predictedblock includes the prediction samples in a spatial domain (or pixeldomain). The predicted block is identically derived in the encodingapparatus and the decoding apparatus. The encoding apparatus can enhanceimage coding efficiency by signaling, to the decoding apparatus,information on a residual (residual information) between the originalblock not an original sample value itself of the original block and thepredicted block. The decoding apparatus may derive a residual blockincluding residual samples based on the residual information, maygenerate a reconstructed including reconstructed samples by adding theresidual block and the predicted block, and may generate a reconstructedpicture including the reconstructed blocks.

The residual information may be generated through a transform andquantization procedure. For example, the encoding apparatus may derivethe residual block between the original block and the predicted block,may derive transform coefficients by performing a transform procedure onthe residual samples (residual sample array) included in the residualblock, may derive quantized transform coefficients by performing aquantization procedure on the transform coefficients, and may signalrelated residual information to the decoding apparatus (through abitstream). In this case, the residual information may includeinformation, such as value information, location information, transformscheme, transform kernel, and quantization parameter of the quantizedtransform coefficients. The decoding apparatus may perform adequantization/inverse transform procedure based on the residualinformation, and may derive residual samples (or residual block). Thedecoding apparatus may generate a reconstructed picture based on thepredicted block and the residual block. Furthermore, the encodingapparatus may derive a residual block bydequantizing/inverse-transforming the quantized transform coefficientsfor reference to the inter prediction of a subsequent picture, and maygenerate a reconstructed picture.

FIG. 4 illustrates an example of an image encoding method performed by avideo encoding apparatus.

Referring to FIG. 4, the image encoding method may include blockpartitioning, intra/inter prediction, transform, quantization andentropy encoding processes. For example, a current picture may bepartitioned into a plurality of blocks. A prediction block of a currentblock may be generated through an intra/inter prediction. A residualblock of the current block may be generated through a subtractionbetween an input block of the current block and the prediction block.Thereafter, a coefficient block, that is, transform coefficients of thecurrent block, may be generated through a transform for the residualblock. The transform coefficients may be quantized and entropy-encodedand stored in a bitstream.

FIG. 5 illustrates an example of a video coding method performed by adecoding apparatus.

Referring to FIG. 5, the image coding method may include entropydecoding, inverse quantization, inverse transform and intra/interprediction processes. For example, the decoding apparatus may performprocesses opposite those of the aforementioned encoding method.Specifically, quantized transform coefficients may be obtained throughentropy decoding for a bitstream. A coefficient block of a currentblock, that is, transform coefficients, may be obtained through aninverse quantization process for the quantized transform coefficients. Aresidual block of the current block may be derived through an inversetransform for the transform coefficients. A reconstructed block of thecurrent block may be derived through the addition of a prediction blockof the current block, derived through an intra/inter prediction, and theresidual block.

Meanwhile, if an intra prediction is performed, a correlation betweensamples may be used, and a difference between the original block and aprediction block, that is, a residual, may be obtained. Theaforementioned transform and quantization may be applied to theresidual. Accordingly, spatial redundancy can be reduced. Hereinafter,an encoding method and a decoding method using an intra prediction arespecifically described.

An intra prediction refers to a prediction for generating predictionsamples for a current block based on reference samples outside thecurrent block within a picture (hereinafter a current picture) includingthe current block. In this case, the reference samples outside thecurrent block may refer to samples located in the periphery of thecurrent block. If an intra prediction is applied to the current block,neighboring reference samples to be used for the intra prediction of thecurrent block may be derived.

For example, when the size (width×height) of a current block is nW×nH,neighboring reference samples of the current block may include a sampleneighboring the left boundary and a total of 2×nH samples neighboringthe bottom left of the current block, a sample neighboring the topboundary and a total of 2×nW samples neighboring the top right of thecurrent block, and one sample neighboring the left top of the currentblock. Alternatively, neighboring reference samples of a current blockmay also include a plurality of columns of top neighboring samples and aplurality of rows of left neighboring samples. Furthermore, neighboringreference samples of a current block may also include a total of nHsamples neighboring the right boundary of the current block having annW×nH size, a total of nW samples neighboring the bottom boundary of thecurrent block and one sample neighboring the bottom right of the currentblock.

In this case, some of the neighboring reference samples of the currentblock have not been decoded or may not be available. In this case, thedecoding apparatus may configure neighboring reference samples to beused for a prediction by substituting unavailable samples with availablesamples. Alternatively, neighboring reference samples to be used for aprediction may be configured through the interpolation of availablesamples.

If neighboring reference samples are derived, (i) a prediction samplemay be derived based on an average or interpolation of the neighboringreference samples of a current block, and (ii) a prediction sample maybe derived based on a reference sample present in a specific(prediction) direction for the prediction sample among neighboringreference samples of a current block. (i) may be applied when an intraprediction mode is a non-directional mode or a non-angular mode. (ii)may be applied when an intra prediction mode is a directional mode or anangular mode.

Furthermore, a prediction sample may be generated through interpolationbetween a first neighboring sample, located in the prediction directionof an intra prediction mode of a current block, and a second neighboringsample corresponding to the first neighboring sample based on aprediction sample of the current block among neighboring referencesamples. The second neighboring sample may be a sample located in adirection opposite the prediction direction of the intra prediction modeof the current block. The above case may be called a linearinterpolation intra prediction (LIP). Furthermore, a temporaryprediction sample of a current block may be derived based on filteredneighboring reference samples. A prediction sample of the current blockmay be derived by weighted-summing at least one reference sample,derived based on an intra prediction mode, and the temporary predictionsample among the existing neighboring reference samples, that is,not-filtered neighboring reference samples. The above case may be calleda position dependent intra prediction (PDCP). Meanwhile, post-filteringfor the derived prediction sample may be performed, if necessary.

Specifically, an intra prediction procedure may include an intraprediction mode determination step, a neighboring reference samplederivation step, and an intra prediction mode-based prediction samplederivation step. Furthermore, a post-filtering step for a derivedprediction sample may be performed, if necessary.

FIG. 6 illustrates an example of an image encoding method based on anintra prediction, and FIG. 7 schematically illustrates an intrapredictor within the encoding apparatus. The intra predictor within theencoding apparatus in FIG. 7 may be applied to the intra predictor (222)of the encoding apparatus (200) in FIG. 2 identically or in acorresponding way.

Referring to FIGS. 6 and 7, step S600 may be performed by the intrapredictor (222) of the encoding apparatus. Step S610 may be performed bythe residual processor (230) of the encoding apparatus. Specifically,step S610 may be performed by the subtractor (231) of the encodingapparatus. At step S620, prediction information may be derived by theintra predictor (222) and may be encoded by the entropy encoder (240).At step S620, residual information may be derived by the residualprocessor (230) and may be encoded by the entropy encoder (240). Theresidual information is information related to residual samples. Theresidual information may include information related to quantizedtransform coefficients for the residual samples. As described above, theresidual samples may be derived as transform coefficients through thetransformer (232) of the encoding apparatus. The transform coefficientsmay be derived as quantized transform coefficients through the quantizer(233). Information related to the quantized transform coefficients maybe encoded by the entropy encoder (240) through a residual codingprocedure.

The encoding apparatus may perform an intra prediction for a currentblock (S600). The encoding apparatus may derive an intra prediction modeof the current block, may derive neighboring reference samples of thecurrent block, and may generate prediction samples within the currentblock based on the intra prediction mode and the neighboring referencesamples. In this case, the intra prediction mode determination,neighboring reference sample derivation and prediction sample generationprocedures may be performed may be performed or any one procedure may beperformed prior to another procedure.

In one embodiment, the intra predictor (222) of the encoding apparatusmay include a prediction mode determiner (223), a reference samplederiver (224), and a prediction sample deriver (225). The predictionmode determiner (223) may determine an intra prediction mode for acurrent block. The reference sample deriver (224) may derive neighboringreference samples of the current block. The prediction sample deriver(225) may derive prediction samples of the current block. Meanwhile,although not illustrated, if a prediction sample filtering procedure tobe described later is performed, the intra predictor (222) may furtherinclude a prediction sample filter unit (not illustrated). The encodingapparatus may determine a mode applied to a current block among aplurality of intra prediction modes. The encoding apparatus may compareRD costs for the intra prediction modes, and may determine the bestintra prediction mode of the current block.

As described above, the encoding apparatus may perform a predictionsample filtering procedure. The prediction sample filtering may becalled post filtering. Some or all of prediction samples may be filteredby the prediction sample filtering procedure. The prediction samplefiltering procedure may be omitted according to circumstances.

The encoding apparatus may generate residual samples for the currentblock based on (filtered) prediction samples (S610). The encodingapparatus may encode image information, including prediction modeinformation indicative of the intra prediction mode and residualinformation related to the residual samples (S620). The encoded imageinformation may be output in a bitstream form. The output bitstream maybe transmitted to the decoding apparatus through a storage medium over anetwork.

As described above, the encoding apparatus may generate a reconstructedpicture (including reconstructed samples and a reconstructed block)based on prediction samples and residual samples. This is for deriving,by the encoding apparatus, the same prediction results as thoseperformed in the decoding apparatus. The reason for this is that codingefficiency can be enhanced. Furthermore, as described above, an in-loopfiltering procedure may be further applied to the reconstructed picture.

FIG. 8 illustrates an example of a video coding method based on an intraprediction, and FIG. 9 schematically illustrates an intra predictorwithin the decoding apparatus. An intra predictor within the decodingapparatus in FIG. 9 may be applied to the intra predictor (331) of thedecoding apparatus (300) in FIG. 3 identically or in a correspondingway.

Referring to FIGS. 8 and 9, the decoding apparatus may performoperations corresponding to the operations performed in the encodingapparatus. The decoding apparatus may perform a prediction on a currentblock and derive prediction samples based on received predictioninformation.

Steps S800 to S820 may be performed by the intra predictor (331) of thedecoding apparatus. In step S830, residual information may be obtainedfrom a bitstream by the entropy decoder (310) of the decoding apparatus.The residual processor (320) of the decoding apparatus may deriveresidual samples for a current block based on the residual information.Specifically, the dequantizer (321) of the residual processor may derivetransform coefficients by performing inverse quantization based onquantized transform coefficients derived based on residual information.The inverse transformer (322) of the residual processor (320) may deriveresidual samples for the current block by performing an inversetransform for the transform coefficients. Step S840 may be performed bythe adder (340) or reconstructor of the decoding apparatus.

The decoding apparatus may derive an intra prediction mode for a currentblock based on received prediction mode information (S800). The decodingapparatus may derive neighboring reference samples of the current block(S810). The decoding apparatus may generate prediction samples within acurrent block based on the intra prediction mode and the neighboringreference samples (S820). In this case, the decoding apparatus mayperform a prediction sample filtering procedure. The prediction samplefiltering may be called post filtering. Some or all of the predictionsamples may be filtered by the prediction sample filtering procedure.The prediction sample filtering procedure may be omitted according tocircumstances.

The decoding apparatus may generate residual samples for the currentblock based on the received residual information (S830). The decodingapparatus may generate reconstructed samples for the current block basedon (filtered) prediction samples and the residual samples, and maygenerate a reconstructed picture based on the reconstructed samples(S840).

In one embodiment, the intra predictor (331) of the decoding apparatusmay include a prediction mode determiner (333), a reference samplederiver (334), and a prediction sample deriver (335). The predictionmode determiner (333) may determine an intra prediction mode for acurrent block based on prediction mode information received from theprediction mode determiner (223) of the encoding apparatus. Thereference sample deriver (334) may derive neighboring reference samplesof the current block. The prediction sample deriver (335) may deriveprediction samples of the current block. Meanwhile, although notillustrated, if the prediction sample filtering procedure is performed,the intra predictor (331) may further include a prediction sample filterunit (not illustrated).

Meanwhile, in performing an intra prediction, prediction modeinformation may be determined depending on whether a most probable mode(MPM) is applied to a current block. For example, the prediction modeinformation may include flag information (e.g.,prev_intra_luma_pred_flag) indicating whether a most probable mode (MPM)is applied or a remaining mode is applied to a current block. If the MPMis applied to the current block, the prediction mode information mayfurther include index information (e.g., mpm_idx) indicative of one ofintra prediction mode candidates (MPM candidates). In this case, theintra prediction mode candidates (MPM candidates) may be configured asan MPM candidate list or an MPM list. Furthermore, if the MPM is notapplied to the current block, the prediction mode information mayfurther include remaining mode information (e.g.,rem_inra_luma_pred_mode) indicative of one of the remaining intraprediction modes except intra prediction mode candidates (MPMcandidates). The decoding apparatus may determine an intra predictionmode of the current block based on the prediction mode information. Inthis case, the prediction mode information may be encoded/decodedthrough a coding method to be described later. For example, theprediction mode information may be encoded/decoded through entropycoding (e.g., CABAC, CAVLC) based on a truncated (rice) binary code.

Furthermore, if an intra prediction is applied, in determiningprediction mode information, an intra prediction mode applied to acurrent block may be determined using an intra prediction mode of aneighboring block. For example, the decoding apparatus may derive mostprobable mode (MPM) candidates based on an intra prediction mode of aleft block and intra prediction mode of a top block of a current block,and may select one of the MPM candidates based on an MPM index (e.g.,mpm_idx). Alternatively, the decoding apparatus may select one of theremaining intra prediction modes, not included in the MPM candidates,based on remaining intra prediction mode information (e.g.,rem_inra_luma_pred_mode). The MPM index may be signaled in the form ofan mpm_idx syntax element. The remaining intra prediction modeinformation may be signaled in the form of a rem_intra_luma_pred_modesyntax element. For example, the remaining intra prediction modeinformation may indicate one of the remaining intra prediction modeswhich are not included in the MPM candidates among all of intraprediction modes and which are indexed in order of a prediction modenumber.

An intra prediction mode may include non-directional (or non-angular)intra prediction modes and directional (or angular) intra predictionmodes. For example, in the HEVC standard, intra prediction modesincluding 2 non-directional prediction modes and 33 directionalprediction modes are used. The non-directional prediction modes mayinclude a planar intra prediction mode, that is, No. 0, and a DC intraprediction mode, that is, No. 1. The directional prediction modes mayinclude No. 2 to No. 34 intra prediction modes. The planar mode intraprediction mode may be called a planar mode, and the DC intra predictionmode may be called a DC mode.

Alternatively, in order to capture a given edge direction proposed innatural video, the directional intra prediction modes may be extendedfrom the existing 33 modes to 65 modes as in FIG. 10. In this case, theintra prediction modes may include 2 non-directional intra predictionmodes and 65 directional intra prediction modes. The non-directionalintra prediction modes may include a planar intra prediction mode, thatis, No. 0, and a DC intra prediction mode, that is, No. 1. Thedirectional intra prediction modes may include Nos. 2 to 66 intraprediction modes. The extended directional intra prediction modes may beapplied to blocks having all sizes, and may be applied to both a lumacomponent and a chroma component. However, this is an example, andembodiments of this specification may be applied to a case where thenumber of intra prediction modes is different. A No. 67 intra predictionmode according to circumstances may be further used. The No. 67 intraprediction mode may indicate a linear model (LM) mode.

FIG. 10 illustrates 65 directional intra prediction modes.

Referring to FIG. 10, modes may be divided into intra prediction modeshaving horizontal directionality and intra prediction modes havingvertical directionality based on a No. 34 intra prediction mode having atop left diagonal prediction direction. In FIG. 10, H and V meanhorizontal directionality and vertical directionality, respectively.Each of numbers −32˜32 indicate displacement of a 1/32 unit on a samplegrid position. The Nos. 2 to 33 intra prediction modes have horizontaldirectionality, and the Nos. 34 to 66 intra prediction modes havevertical directionality. The No. 18 intra prediction mode and the No. 50intra prediction mode indicate a horizontal intra prediction mode and avertical intra prediction mode, respectively. The No. 2 intra predictionmode may be called a bottom left diagonal intra prediction mode, the No.34 intra prediction mode may be called a top left diagonal intraprediction mode, and the No. 66 intra prediction mode may be called atop right diagonal intra prediction mode.

As described above, in general, if block partitioning for a picture isperformed, a current block and a neighboring block to be coded havesimilar image characteristics. Accordingly, there is a good probabilitythat the current block and the neighboring block will have the same orsimilar intra prediction mode. According to such image characteristics,an intra prediction mode of a current block may be derived using anintra prediction mode of a neighboring block. This may be referred to asa most probable mode (MPM). That is, the MPM may mean a mode used toenhance coding efficiency by considering similarity between a currentblock and a neighboring block upon intra prediction mode coding.

For example, the encoding/decoding apparatus may configure a mostprobable mode (MPM) list for a current block. The MPM list may beindicated as an MPM candidate list. In this case, an MPM list includinggiven MPM candidates may be configured by considering complexity ingenerating the MPM list. For example, an MPM list may include 3 MPMcandidates, 5 candidates or 6 MPM candidates. In one embodiment, an MPMlist may include MPM candidates derived based on an intra predictionmode of a neighboring block, a derived intra prediction mode and/or adefault intra prediction mode. In this case, in deriving MPM candidatesfrom the neighboring block, the encoding apparatus/decoding apparatusmay derive an intra prediction mode of the neighboring block bysearching neighboring blocks of a current block according to a specificorder, and may use the intra prediction mode of the neighboring block asan MPM candidate based on the derived order. For example, theneighboring blocks may include at least one of the left neighboringblock, top neighboring block, bottom left neighboring block, top rightneighboring block, and top-left neighboring block of the current block.If an intra prediction mode of the current block is not included amongthe MPM candidates within the MPM list, a remaining mode may be used. Inthis case, the remaining mode is a mode using the remaining intraprediction modes except the MPM candidates, among all of intraprediction modes, and may code and signal remaining intra predictionmode information. The remaining intra prediction mode information may beinformation indicative of an intra prediction mode applied to a currentblock, among the remaining intra prediction modes except the MPMcandidates. For example, if 67 intra prediction modes are used, theremaining intra prediction mode information may include a 6-bit syntaxelement (e.g., rem_intra_luma_pred_mode syntax element).

As described above, in the HEVC standard, 35 intra prediction modes areused upon intra prediction. In this case, an MPM list including 3 MPMcandidates is configured. In this case, the 3 MPM candidates may bederived based on intra prediction modes of a neighboring block F andneighboring block G. Neighboring blocks of a current block including theneighboring block F and the neighboring block G may be the same as thosedescribed above.

FIG. 11 illustrates neighboring blocks of a current block.

Referring to FIG. 11, neighboring blocks of a current block may includea neighboring block A, a neighboring block B, a neighboring block C, aneighboring block D, a neighboring block E, a neighboring block F and/ora neighboring block G.

In this case, the neighboring block A may indicate a neighboring blocklocated on the top left side of a top-left sample position of a currentblock. The neighboring block B may indicate a neighboring block locatedon the upper side of a top right sample position of the current block.The neighboring block C may indicate a neighboring block located on thetop right side of a top right sample position of the current block. Theneighboring block D may indicate a neighboring block located on the leftside of a bottom left sample position of the current block. Theneighboring block E may indicate a neighboring block located on thebottom left of a bottom left sample position of the current block. Theneighboring block G may indicate a neighboring block located on theupper side of a top-left sample position of the current block. Theneighboring block F may indicate a neighboring block located on the leftside of a top-left sample position of the current block.

For example, if the size of a current block is W×H and the x componentand y component of the top-left sample position of the current block are0, the neighboring block A may be a block including a sample at (−1, −1)coordinates, the neighboring block B may be a block including a sampleat (W−1, −1) coordinates, the neighboring block C may be a blockincluding a sample at (W, −1) coordinates, the neighboring block D maybe a block including a sample at (−1, H−1) coordinates, the neighboringblock E may be a block including a sample at (−1, H) coordinates, theneighboring block F may be a block including a sample at (−1, 0)coordinates, and the neighboring block G may be a block including asample at (0, −1) coordinates.

According to the HEVC standard, 3 MPM candidates may be derived based onan intra prediction mode of the neighboring block F and an intraprediction mode of the neighboring block G. For example, the intraprediction mode of the neighboring block F and the intra prediction modeof the neighboring block G may be derived. Meanwhile, in the followingcase, an intra prediction mode of the neighboring block F or an intraprediction mode of the neighboring block G may be derived as a DC intraprediction mode.

1) If the neighboring block F or the neighboring block G is notavailable

2) If the neighboring block F or the neighboring block G is not coded asan intra prediction mode (i.e., if the neighboring block F or theneighboring block G is not an intra coded block)

3) If the neighboring block F or the neighboring block G is out of acurrent coding tree unit (CTU)

If an intra prediction mode of the neighboring block F or an intraprediction mode of the neighboring block G is determined as describedabove, 3 MPM candidates may be derived like Table 1.

TABLE 1 if (intra mode of F and G are equal) { if (intra mode of F <intra mode 2) { MPM list1 } else { MPM list2 } } else { if (Neitherintra mode of F nor G are intra mode Planar) { MPM list3 } else if(intra mode of (F+G) <intra mode 2) { MPM list4 } else { MPM list5 } }

Table 1 illustrates a schematic algorithm (i.e., pseudo code) forconfiguring an MPM list. Referring to Table 1, whether the intraprediction mode of the neighboring block F and the intra prediction modeof the neighboring block G are equal may be determined.

If an intra prediction mode of the neighboring block F and an intraprediction mode of the neighboring block G are equal and the mode numberof an intra prediction mode of the neighboring block F is smaller than2, the MPM list of the current block may be derived as an MPM list 1(MPM list1). That is, if an intra prediction mode of the neighboringblock F and an intra prediction mode of the neighboring block G areequal and the intra prediction mode of the neighboring block F is theintra prediction mode of the mode number 0 or the intra prediction modeof the mode number 1, the MPM list of the current block may be derivedas the MPM list 1. In this case, the MPM list 1 may indicate an MPM listconfigured with MPM candidates {F, F−1, F+1}. F may indicate the intraprediction mode of the neighboring block F. F−1 may indicate an intraprediction mode in which a value obtained by subtracting 1 from the modenumber of an intra prediction mode of the neighboring block F is a modenumber. F+1 may indicate an intra prediction mode in which a valueobtained by adding 1 to the mode number of an intra prediction mode ofthe neighboring block F is a mode number. For example, if the intraprediction mode of the neighboring block F is the intra prediction modeof the mode number N, the MPM list 1 may be configured with an MPM list,including the intra prediction mode of the mode number N, the intraprediction mode of the mode number N−1, and the intra prediction mode ofthe mode number N+1 as MPM candidates.

Furthermore, if an intra prediction mode of the neighboring block F andan intra prediction mode of the neighboring block G are equal and themode number of an intra prediction mode of the neighboring block F isnot smaller than 2, the MPM list of the current block may be derived asan MPM list 2 (MPM list2).

Furthermore, if an intra prediction mode of the neighboring block F andan intra prediction mode of the neighboring block G are not equal andthe intra prediction mode of the neighboring block F and the intraprediction mode of the neighboring block G are not planar mode intraprediction modes, the MPM list of the current block may be derived as anMPM list 3 (MPM list3).

Furthermore, if an intra prediction mode of the neighboring block F andan intra prediction mode of the neighboring block G are not equal andthe sum of the mode number of an intra prediction mode of theneighboring block F and the mode number of an intra prediction mode ofthe neighboring block G is smaller than 2, the MPM list of the currentblock may be derived as an MPM list 4 (MPM list4).

Furthermore, if an intra prediction mode of the neighboring block F andan intra prediction mode of the neighboring block G are not equal and atleast one of the intra prediction mode of the neighboring block F andthe intra prediction mode of the neighboring block G is a planar modeintra prediction mode and the sum of the mode number of an intraprediction mode of the neighboring block F and the mode number of anintra prediction mode of the neighboring block G is not smaller than 2,the MPM list of the current block may be derived as an MPM list 5 (MPMlist5).

Meanwhile, as the number of intra prediction modes increases, the numberof MPM candidates needs to be increased. Accordingly, the number of MPMcandidates may be different depending on the number of intra predictionmodes. In general, when the number of intra prediction modes increases,the number of MPM candidates may increase. However, the number of MPMcandidates does not always increase when the number of intra predictionmodes increases. For example, if 35 intra prediction modes are presentor if 67 intra prediction modes are present, various numbers of MPMcandidates, such as 3, 4, 5, and 6, may be present depending on thedesign.

For example, a 6-MPM list configuration may be performed. That is, anMPM list including 6 MPM candidates may be configured. For example, inthe 6-MPM list configuration, a process of searching for the locationsof various neighboring blocks and a consistent pruning check process forexcluding the same intra prediction mode may be performed. For example,the order in which 6 MPM candidates are configured may be as follows:

The neighboring block D, the neighboring block B, the planar mode intraprediction mode, the DC intra prediction mode, the neighboring block E,the neighboring block C, and the neighboring block A.

That is, neighboring blocks may be derived as MPM candidate in order ofan intra prediction mode of the neighboring block D, an intra predictionmode of the neighboring block B, the planar mode intra prediction mode,the DC intra prediction mode, an intra prediction mode of theneighboring block E, an intra prediction mode of the neighboring blockC, and an intra prediction mode of the neighboring block A. If aprediction mode is the same as an already derived intra prediction mode,it may not be derived as an MPM candidate.

Furthermore, if an MPM list does not include an MPM candidate having amaximum number of candidates, that is, when the number of derived MPMcandidates is smaller than a maximum number of candidates, a directionalintra prediction mode neighboring a derived MPM candidate and apre-defined default intra prediction mode may be considered as MPMcandidates, and a pruning check process may be performed. In this case,the directional intra prediction mode neighboring the MPM candidate mayindicate an intra prediction mode having a mode number neighboring thatof the MPM candidate. The neighboring block search and the consistentpruning check have an advantage in the reduction of a bit transfer rate,but may increase the number of hardware operation cycles for the MPMlist configuration of each block. The worst scenario is that a 3840×21604K image may be partitioned into 4×4 size blocks for an intraprediction. In this case, an increased hardware operation cycle for eachof the 4×4 size blocks may be importantly considered in throughput.Meanwhile, if a neighboring block coded through an inter prediction isaware of an intra prediction mode of the neighboring block, the intraprediction mode of the neighboring block may be used for an MPM listconfiguration.

As described above, in configuring an MPM list, the encoding apparatusmay determine the best intra prediction mode by optimizing the bit rateand distortion at the same time, and may code the determined best intraprediction mode as a bitstream. The decoding apparatus may parse(decode) the intra prediction mode included in the bitstream, and mayperform an intra prediction based on the parsed intra prediction mode.However, in order to minimize signaling overhead as the number of intraprediction modes increases, efficient intra mode coding is necessary.Both the encoding apparatus and the decoding apparatus configure MPMlists using neighboring intra prediction modes of coded blocks. In thiscase, when the best intra prediction mode is one of candidates withinthe MPM list, overhead can be minimized by signaling an MPM index. Thelength of the MPM list and the method of configuring the MPM list may bedifferent depending on an algorithm.

In this case, if the 67 intra prediction modes are used for an intraprediction, the MPM list including the existing 3 MPM candidates may notbe sufficient to show the diversity of multiple intra prediction modes.Furthermore, a 6-MPM list configuration scheme including neighboringblock search and a pruning check process may affect throughput becauseit is too complicated. Accordingly, embodiments of this specificationpropose efficient the MPM list configuration method having a properbalance between complexity and coding efficiency.

FIGS. 12 and 13 are flowcharts schematically illustrating a method ofconfiguring an MPM list for a current block.

Referring to FIGS. 12 and 13, an MPM list for a current block includingk MPM candidates may be configured. In this case, k may indicate thelength of the MPM list, that is, the number of MPM candidates includedin the MPM list. According to the embodiments disclosed in FIGS. 12 and13, 5 efficient MPM lists (MPM list 1 MPM˜list 5) may be configuredbased on five conditions. That is, one of the 5 MPM lists may be derivedas an MPM list for the current block based on the five conditions. TheMPM lists may be independent lists as illustrated in FIG. 12, and may belists having partially shared portions as illustrated in FIG. 13. If apartial list shared as in FIG. 13 is used, a duplication process can beavoided. The conditions 5 may be modeled so that the sum of theprobabilities of all the conditions become 1.

FIG. 14 is a flowchart illustrating an embodiment of a method ofconfiguring an MPM list for a current block.

FIG. 14 illustrates a method of efficiently configuring an MPM list fora current block including k MPM candidates based on a neighboring blocklocated adjacent to the current block. For example, k may be 6, and fiveconditions may be used in order to configure an MPM list for the currentblock among 5 efficient lists. In FIG. 14, L may indicate an intraprediction mode of the neighboring block B illustrated in FIG. 11, and Amay indicate an intra prediction mode of the neighboring block Dillustrated in FIG. 11. Alternatively, in contrast, L may indicate anintra prediction mode of the neighboring block D illustrated in FIG. 11,and A may indicate an intra prediction mode of the neighboring block Billustrated in FIG. 11. In FIG. 14, a symbol “!” is a negative logicoperator, and may refer to an operator “not” that converts a value thatis not true into a true value, and the vice versa. For example, !7 mayindicate a value 0, and !0 may indicate a value 1.

Referring to FIG. 14, the encoding/decoding apparatus may check acondition 1 for determining whether L and A are equal (S1400). That is,the encoding/decoding apparatus may determine whether L and A are thesame intra prediction mode. The condition 1 may be a condition fordetermining whether “L==A”.

If L and A are the same intra prediction mode (i.e., when the condition1 is satisfied), the encoding/decoding apparatus may check a condition 2for determining whether L (or A) is a directional intra prediction mode(S1405). That is, the encoding/decoding apparatus may determine whetherL and A are equal and the mode number of L (or A) is greater than themode number of a DC mode. The condition 2 may be a condition fordetermining whether “L>DC_idx”.

When the condition 2 is satisfied, the encoding/decoding apparatus mayderive an MPM list 1 as an MPM list for the current block (S1410). Whenthe condition 2 is not satisfied, the encoding/decoding apparatus mayderive an MPM list 2 as an MPM list for the current block (S1415).

In this case, the MPM list 1 may be configured like Table 2, and the MPMlist 2 may be configured like Table 3.

TABLE 2 mpm[0] = L mpm[2] = Planar_idx mpm[3] = DC_idx mpm[3] = L − 1mpm[4] = L + 1 mpm[5] = L − 2

TABLE 3 mpm[0] = L mpm[1] = ! L mpm[2] = Vertical_idx mpm[3] =Horizontal_idx mpm[4] = Vertical_idx − 4 mpm[5] = Vertical_idx + 4

Referring to Table 2 and Table 3, the MPM list 1 may include a first MPMcandidate (mpm[0]) to a sixth MPM candidate (mpm[5]) as in Table 2, TheMPM list 2 may include a first MPM candidate (mpm[0]) to a sixth MPMcandidate (mpm[5]) as in Table 3. In this case, the first to sixth MPMcandidates may indicate intra prediction modes (i.e., mode numbers)indicated by respective MPM index values 0 to 5. For example, the firstMPM candidate indicates an intra prediction mode assigned to mpm[0], andmay be indicated the value 0 of an MPM index.

If L and A are not the same intra prediction mode (i.e., when thecondition 1 is not satisfied), the encoding/decoding apparatus mayderive a partially shared MPM list 1 (S1420).

In this case, the partially shared MPM list 1 may be configured likeTable 4.

TABLE 4 mpm[0] = L mpm[1] = A If L > A, max_idx is 0 and min_idx is 1.Otherwise, max_idx is 1 and min_idx is 0.

Referring to Table 4, the partially shared MPM list 1 may include afirst MPM candidate (mpm[0]) indicative of L and a second MPM candidate(mpm[1]) indicative of A. That is, if L and A are not equal, theencoding/decoding apparatus may first add L and A to the MPM list.Accordingly, MPM lists 3, 4, and 5 to be described later may beconfigured to partially include the first MPM candidate (mpm[0]) and thesecond MPM candidate (mpm[1]) as in Table 4. In this case, in derivingthe first MPM candidate (mpm[0]) and the second MPM candidate (mpm[1]),an MPM index order may be determined by comparing the sizes of the modenumbers of L and A. For example, referring to Table 4, when L has agreater mode number than A, a max_idx value indicative of L may be setto 0, and a min_idx value indicative of A may be set to 1. When L has asmaller mode number than A, max_idx and min_idx values may be inverselyset.

Next, the encoding/decoding apparatus may check a condition 3 fordetermining whether both L and A are directional intra prediction modes(S1425). That is, the encoding/decoding apparatus may determine whetherL and A are not equal and the mode number of each of L and A is greaterthan a DC mode number. The condition 3 may be a condition fordetermining whether “L>DC_idx AND A>DC_idx”.

If each of L and A has a greater mode number than the DC mode (i.e.,when the condition 3 is satisfied), the encoding/decoding apparatus mayderive a partially shared MPM list 2 (S1440).

In this case, the partially shared MPM list 2 may be configured likeTable 5.

TABLE 5 mpm[2] = Planar_idx mpm[3] = DC_idx diff = mpm[max_idx] −mpm[min_idx]

Referring to Table 5, the partially shared MPM list 2 may include athird MPM candidate (mpm[2]) indicative of a planar mode and a fourthMPM candidate (mpm[3]) indicative of a DC mode. That is, if thecondition 3 is satisfied, this means that both L and A are directionalintra prediction modes. Accordingly, the encoding/decoding apparatus mayadd the planar mode and the DC mode, that is, not directional intraprediction modes, to the MPM list as the third MPM candidate (mpm[2])and the fourth MPM candidate (mpm[3]) after the first MPM candidate(mpm[0]=L) and the second MPM candidate (mpm[1]=A) included in thepartially shared MPM list 1 described in Table 4. Accordingly, MPM lists4 and 5 to be described later may be configured to partially include thethird MPM candidate (mpm[2]) and the fourth MPM candidate (mpm[3]) inTable 5 along with the first MPM candidate (mpm[0]) and the second MPMcandidate (mpm[1]) in Table 4.

Next, the encoding/decoding apparatus may check a condition 4 fordetermining whether a difference between the mode number of L and themode number of A is not 64 and not 1 (S1445). The condition 4 may be acondition for determining whether “diff !=64 AND diff !=1”.

For example, the difference (diff) between the mode number of L and themode number of A may be calculated like an equation illustrated in Table5. In this case, diff may be a result obtained by subtracting a smallervalue from a greater value in the mode number of L and the mode numberof A.

In this case, when the condition 4 is satisfied, the encoding/decodingapparatus may derive an MPM list 5 as an MPM list for the current block(S1455). When the condition 4 is not satisfied, the encoding/decodingapparatus may derive an MPM list 4 as an MPM list for the current block(S1450).

In this case, the MPM list 4 may be configured like Table 6, and the MPMlist 5 may be configured like Table 7.

TABLE 6 mpm[4] = mpm[max_idx] − 2 mpm[5] = mpm[max_idx] + 2

TABLE 7 mpm[4] = mpm[max_idx] − 1 mpm[5] = mpm[max_idx] + 1

Each of the MPM list 4 of Table 6 and the MPM list 5 of Table 7 may beconfigured to include a fifth MPM candidate (mpm[4]) and a sixth MPMcandidate (mpm[5]) along with the first to fourth MPM candidates(mpm[0]˜ mpm[3]) described in Table 4 and Table 5.

Meanwhile, if at least one of L and A is a non-directional intraprediction mode at step S1425 (i.e., when the condition 3 is notsatisfied), the encoding/decoding apparatus may check a condition 5 fordetermining whether only any one of L and A is a non-directional intraprediction mode (S1430). That is, the encoding/decoding apparatus maydetermine whether at least one of L and A is a DC mode number or lessand the sum of the mode number of L and the mode number of A is 2 ormore. The condition 5 may be a condition for determining whether“L+A>=2”.

When the sum of the mode number of L and the mode number of A is 2 ormore (i.e., when the condition 5 is satisfied), the encoding/decodingapparatus may derive an MPM list 3 as an MPM list for the current block(S1435).

In this case, the MPM list 3 may be configured like Table 8.

TABLE 8 mpm[2] = ! mpm[min_idx] mpm[3] = mpm[max_idx] − 1 mpm[4] =mpm[max_idx] + 1 mpm[5] = mpm[max_idx] − 2

Referring to Table 8, the MPM list 3 may be configured to include thirdto sixth MPM candidates (mpm[2]˜mpm[5]) along with the first MPMcandidate (mpm[0]) and the second MPM candidate (mpm[1]) described inTable 4. In this case, to satisfy the condition 5 may mean that any oneof L and A is a directional prediction mode and the other is anon-directional prediction mode. Accordingly, the MPM list 3 may includea non-directional prediction mode as the third MPM candidate (mpm[2])after the first and second MPM candidates. For example, if one having anon-directional mode, among L and A, is a planar mode, the third MPMcandidate (mpm[2]) may be derived as a DC mode. Alternatively, if onehaving a non-directional mode, among L and A, is a DC mode, the thirdMPM candidate (mpm[2]) may be derived as a planar mode.

When the sum of the mode number of L and the mode number of A is not 2or more (i.e., when the condition 5 is not satisfied), theencoding/decoding apparatus may derive an MPM list 2 as an MPM list forthe current block (S1415). In this case, both L and A may benon-directional prediction modes.

In this case, the MPM list 2 may be the same as Table 3. Referring toTable 3, since both L and A are non-directional prediction modes, in theMPM list 2, a planar mode and a DC mode may be derived as the first MPMcandidate (mpm[0]) and the second MPM candidate (mpm[1]), respectively.The remaining third to sixth MPM candidates (mpm[2]˜ mpm[5]) may bederived as illustrated in Table 3.

In Table 2 to Table 8, in (directional intra prediction mode+1),(directional intra prediction mode−1), (directional intra predictionmode+2), (directional intra prediction mode−2), and so on, a value maybe mathematically added or subtracted. However, in some cases,mathematical calculation may not be simply performed. For example, in anon-directional intra prediction mode, the consistency of a neighboringintra prediction mode may not be maintained by subtracting or adding adirectional intra prediction mode or a maximum available intraprediction mode index may be exceeded. For example, a value obtained bysubtracting 1 from a directional intra prediction mode may be derived asan intra mode 1 indicative of a DC index (DC mode). 7 is obtained byadding 1 to the No. 66 directional intra prediction mode, and thus itexceeds the index 66 of a maximum available intra mode. Accordingly, anoperation of adding or subtracting a mode may be limited as followsusing a modular arithmetic (indicated by %). That is, a value indicativeof a non-directional intra prediction mode that does not consistency ora value that exceeds a maximum available intra mode index can beprevented from being derived. For example, the adding or subtracting ofa mode using the modular arithmetic may be derived like Table 9.

TABLE 9 Intra mode −1: (Intra mode +62)%65 + 2 Intra mode +1: (Intramode −1)%65 + 2 Intra mode −2: (Intra mode +61)%65 + 2

The method of configuring an MPM list in the aforementioned embodimentsmay be performed in the encoding/decoding apparatus. In this case, inconfiguring the MPM list, the encoding apparatus may derive the bestintra prediction mode to be applied to a current block, and maydetermine whether the derived best intra prediction mode belongs to anMPM list including MPM candidates configured using a method, such asthose of the aforementioned embodiments. If an intra prediction mode ofa current block belongs to an MPM list including MPM candidates, theencoding apparatus may encode an MPM flag and an MPM index. In thiscase, the MPM flag may indicate whether the intra prediction mode of thecurrent block belongs to the MPM list (i.e., MPM candidates). The MPMindex may indicate whether which MPM mode is applied as the intraprediction mode of the current block, among the MPM candidates includedin the MPM list. In contrast, if the intra prediction mode of thecurrent block does not belong to the MPM list including the MPMcandidates, the encoding apparatus may encode the intra prediction modeof the current block.

The decoding apparatus may configure an MPM list by applying the samemethod as that of the aforementioned embodiments identically with theencoding apparatus. Furthermore, the decoding apparatus may receive anMPM flag from the encoding apparatus, and may identify whether an intraprediction mode applied to a current block is included in an MPM list(i.e., MPM candidates) using the MPM flag. If the intra prediction modeapplied to the current block is included within the MPM list (i.e., MPMcandidates), the decoding apparatus may derive an intra prediction modeapplied to the current block using an MPM index received from theencoding apparatus. In contrast, if the intra prediction mode applied tothe current block is not included in the MPM list (i.e., MPMcandidates), the decoding apparatus may derive an intra prediction modeapplied to the current block using a prediction mode index (or,remaining prediction mode index; remaining mode information) indicativeof a specific prediction mode, among remaining prediction modes exceptthe MPM candidates.

Hereinafter, there is proposed a method of configuring an extended MPMlist having similar complexity by comparing the extended MPM list withan MPM list including 3 MPM candidates. The extended MPM list refers toa MPM list including three or more MPM candidates, and may include 3, 4,5 or 6 MPM candidates, for example. In a proposed method to be describedlater, an embodiment in which an MPM list including 6 MPM candidates isgenerated using two neighboring intra prediction modes (left neighboringintra prediction mode and above neighboring intra prediction mode). Inthis case, the left neighboring intra prediction mode (LEFT) mayindicate an intra prediction mode of the neighboring block D in FIG. 11,and the above neighboring intra prediction mode (ABOVE) may indicate anintra prediction mode of the neighboring block B in FIG. 11.

In configuring the extended MPM list, the reason for the 3 MPMcandidates are used is that there are advantages in simplicity andthroughput. However, complexity may be increased because the existingmethod using 6 MPM candidates includes a process of searching for thelocations of various neighboring blocks, a continuous pruning process,steps for generating the MPM list, line buffer requirements and parsingdependency. Accordingly, as in the method using 3 MPM candidates, thereis proposed a method capable of obtaining advantages in complexity andthroughput even in using 6 MPM candidates.

In one embodiment, an MPM list may be configured based on an algorithm(i.e., pseudo code), such as Table 10.

TABLE 10 Determine LEFT and ABOVE intra modes Set MPM as MPM_ordering_0If (LEFT==ABOVE) If (LEFT>=DC_idx), then set MPM as MPM_ordering_1 Elseif (LEFT>DC_idx and ABOVE>DC_idx), then set MPM as MPM_ordering_2 Elseif (LEFT+ABOVE> DC_idx), then set MPM as MPM_ordering_3

Referring to Table 10, the MPM list of a current block may be generatedbased on LEFT and ABOVE, that is, neighboring intra prediction modes. Inthis case, LEFT may indicate an intra prediction mode of the neighboringblock D in FIG. 11, and ABOVE may indicate an intra prediction mode ofthe neighboring block B in FIG. 11. Furthermore, the neighboring block Dmay indicate a left neighboring block located on the downmost side,among left neighboring blocks neighboring the left of the current block.The neighboring block B may indicate a top neighboring block located onthe far right (or rightmost) side, among neighboring blocks neighboringthe top of the current block.

Specifically, intra prediction modes of LEFT and ABOVE may be derived.Furthermore, the MPM list (i.e., MPM candidates) of a current block maybe set as MPM_ordering_0 based on the intra prediction modes of LEFT andABOVE. In this case, if LEFT and ABOVE are equal and the mode number ofLEFT is greater than or equal to a DC mode, the MPM list (i.e., MPMcandidates) of the current block may be set as MPM_ordering_1.Alternatively, if LEFT and ABOVE are not equal and the mode number ofLEFT is greater than that of a DC mode and the mode number of ABOVE isgreater than that of a DC mode, the MPM list (i.e., MPM candidates) ofthe current block may be set as MPM_ordering_2. Alternatively, if LEFTand ABOVE are not equal, at least one of the mode number of LEFT and themode number of ABOVE is not greater than that of a DC mode, and the sumof the mode number of LEFT and the mode number of ABOVE is greater thanthe mode number of a DC mode, the MPM list (i.e., MPM candidates) of thecurrent block may be set as MPM_ordering_3.

In this case, MPM_ordering_0, MPM_ordering_1, MPM_ordering_2, orMPM_ordering_3 may have been configured to include MPM candidatesaccording to a predetermined order as described in FIGS. 12 to 14

Furthermore, if one of the remaining intra prediction modes exceptderived MPM candidates is an intra prediction mode applied to a currentblock as described above, the MPM coding of the current block may beperformed based on remaining mode information. Such remaining modeinformation may be encoded/decoded by applying truncated binary (TB)coding.

In another embodiment, an MPM list may be configured based on analgorithm (i.e., spec), such as Table 11.

Referring to Table 11, candidate intra prediction modes may be derivedbased on a neighboring block of a current block. An MPM list for thecurrent block may be configured based on the candidate intra predictionmodes. The candidate intra prediction modes may include a candidateintra prediction mode A and a candidate intra prediction mode B.

For example, when at least one of conditions to be described later istrue (i.e., when at least one of conditions to be described later issatisfied, the candidate intra prediction mode A may be set as a planarmode intra prediction mode.

-   -   A neighboring block A is not available    -   An intra prediction is not applied to the neighboring block A

In this case, the neighboring block A may be a left neighboring block ofa current block. The left neighboring block may be a left neighboringblock located on the downmost side, among left neighboring blocksneighboring the current block. For example, if the size of a currentblock is cbWidth×cbHeight and an x component and y component at thetop-left sample position of the current block are xCb and yCb, theneighboring block A may be a block including a sample at (xCb−1,yCb+cbHeight−1) coordinates. Meanwhile, the neighboring block A mayindicate the neighboring block D of FIG. 11.

When all the conditions are not true (i.e., when all the conditions arenot satisfied), the candidate intra prediction mode A may be set as anintra prediction mode of the neighboring block A.

Furthermore, for example, when at least one of conditions to bedescribed later is true (i.e., when at least one of the conditions to bedescribed later is satisfied, the candidate intra prediction mode B maybe set as a planar mode intra prediction mode.

-   -   A neighboring block B is not available    -   An intra prediction is not applied to the neighboring block B    -   yCb−1 is smaller than ((yCb>>CtbLog2SizeY)<<CtbLog2SizeY)

In this case, the neighboring block B may be a top neighboring block ofthe current block. The top neighboring block may be a top neighboringblock located on the far right (or rightmost) side among top neighboringblocks neighboring the current block. For example, if the size of acurrent block is cbWidth×cbHeight and an x component and y component atthe top-left sample position of the current block are xCb and yCb, theneighboring block B may be a block including a sample at (xCb+cbWidth−1,yCb−1) coordinates. Meanwhile, CtbLog2SizeY may indicate the size of acurrent CTU, and ((yCb>>CtbLog2SizeY)<<CtbLog2SizeY) may indicatecoordinates at the top boundary of the current CTU. That is, a casewhere yCb−1 is smaller than ((yCb>>CtbLog2SizeY)<<CtbLog2SizeY) mayindicate a case where the neighboring block B is out of the range of thecurrent CTU. That is, the aforementioned condition may indicate a casewhere the neighboring block B is out of the range of the current CTU.

When all the conditions are not true (i.e., when all the conditions arenot satisfied), the candidate intra prediction mode B may be set as anintra prediction mode of the neighboring block B.

If candidate intra prediction modes have been derived, the MPM list ofthe current block may be configured like a first MPM list. The first MPMlist may be configured with a first MPM candidate indicative of acandidate intra prediction mode A, a second MPM candidate indicative ofthe intra prediction mode of a value obtained by performing an operationon the candidate intra prediction mode A using a negative logicoperator, a third MPM candidate indicative of the No. 50 intraprediction mode, a fourth MPM candidate indicative of the No. 18 intraprediction mode, a fifth MPM candidate indicative of the No. 46 intraprediction mode, and a sixth MPM candidate indicative of the No. 54intra prediction mode.

Thereafter, whether the candidate intra prediction mode B and thecandidate intra prediction mode A are equal may be determined.

In this case, if the candidate intra prediction mode B and the candidateintra prediction mode A are equal, whether the candidate intraprediction mode A is larger than 1 may be determined. When the candidateintra prediction mode A is larger than 1, the MPM list of the currentblock may be configured like a second MPM list. The second MPM list maybe configured with a first MPM candidate indicative of the candidateintra prediction mode A, a second MPM candidate indicative of a planarmode intra prediction mode, a third MPM candidate indicative of a DCintra prediction mode, a fourth MPM candidate indicative of an intraprediction mode derived as 2+((candIntraPredModeA+62) % 65), a fifth MPMcandidate indicative of an intra prediction mode derived as2+((candIntraPredModeA−1) % 65), and a sixth MPM candidate indicative ofan intra prediction mode derived as 2+((candIntraPredModeA+61) % 65).

Otherwise, if the candidate intra prediction mode B and the candidateintra prediction mode A are not equal, first, the first MPM candidateand second MPM candidate of the current block may be derived. The firstMPM candidate may be derived as the candidate intra prediction mode A,and the second MPM candidate may be derived as the candidate intraprediction mode B. Furthermore, biggerIdx may be set. When the first MPMcandidate is greater than the second MPM candidate, biggerIdx may bederived as 0. When the first MPM candidate is not greater than thesecond MPM candidate, biggerIdx may be derived as 1.

Next, whether the candidate intra prediction mode A and the candidateintra prediction mode B are larger than 1 may be determined (i.e.,whether the mode number of the candidate intra prediction mode A and themode number of the candidate intra prediction mode B are larger than 1may be determined). In this case, when the candidate intra predictionmode A and the candidate intra prediction mode B are larger than 1, thethird MPM candidate and fourth MPM candidate of the current block may bederived. The third MPM candidate may be derived as a planar mode intraprediction mode, and the fourth MPM candidate may be derived as a DCintra prediction mode.

Next, whether a difference (diff) between an MPM candidate indicated byan MPM index having a value of biggerIdx and an MPM candidate indicatedby an MPM index having a value (i.e., !biggerIdx) obtained by performingan operation on biggerIdx using a negative logic operator is not 64 andalso not 1 may be determined.

When the difference is not 64 and also not 1, the fifth MPM candidateand sixth MPM candidate of the current block may be derived. The fifthMPM candidate may be derived as an intra prediction mode derived as2+((candModeList[biggerIdx]+62) % 65). The sixth MPM candidate may bederived as an intra prediction mode derived as2+((candModeList[biggerIdx]−1) % 65).

Otherwise, if the difference is 64 or 1, the fifth MPM candidate andsixth MPM candidate of the current block may be derived. The fifth MPMcandidate may be derived as an intra prediction mode derived as2+((candModeList[biggerIdx]+61) % 65). The sixth MPM candidate may bederived as an intra prediction mode derived as2+(candModeList[biggerIdx]% 65).

Meanwhile, when the sum of the candidate intra prediction mode A and thecandidate intra prediction mode B is greater than or equal to 2, thethird MPM candidate, fourth MPM candidate, fifth MPM candidate and sixthMPM candidate of the current block may be derived. The third MPMcandidate may be derived as an intra prediction mode derived as a valueobtained by performing an operation on an MPM candidate, indicated by anMPM index having a value (i.e., !biggerIdx) by performing an operationon biggerIdx using a negative logic operator, using a negative logicoperator. The fourth MPM candidate may be derived as an intra predictionmode derived as 2+((candModeList[biggerIdx]+62) % 65). The fifth MPMcandidate may be derived as an intra prediction mode derived as2+((candModeList[biggerIdx]−1) % 65). The sixth MPM candidate may bederived as an intra prediction mode derived as2+((candModeList[biggerIdx]+61) % 65).

An intra prediction mode for the current block may be derived based onan MPM list including MPM candidates, which are derived as describedabove. And, based on the derived intra prediction mode, prediction ofthe current block may be performed so as to generate predicted samples.

At this point, when deriving intra prediction modes for the currentblock, in case an MPM flag (e.g., intra_luma_mpm_flag of Table 11) isequal to 1, among the MPM candidates that are derived as describedabove, an MPM candidate being indicated by an MPM index (e.g.,intra_luma_mpm_idx of Table 11) may be derived as the intra predictionmode of the current block. Alternatively, in case an MPM flag (e.g.,intra_luma_mpm_flag of Table 11) is equal to 0, based on a remainingmode (e.g., intra_luma_mpm_remainder of Table 11) indicating one intraprediction mode among the remainder intra prediction modes excluding theMPM candidates that are derived as described above, the one intraprediction mode may be derived as the intra prediction mode of thecurrent block.

As described above, intra prediction mode information for the currentblock may be coded to a syntax element value and may then be signaled.Herein, intra prediction mode information refers to information that isneeded for the intra prediction of the current block, wherein theinformation may include the above-described MPM flag, MPM index,remaining mode, and so on. When coding the intra prediction modeinformation, various binarization processes may be applied in accordancewith each syntax element.

Herein, binarization may mean a set of bin strings for all feasiblevalues of a syntax element. Additionally, a binarization process maymean a procedure for uniquely mapping all feasible values of a syntaxelement to a set of bin strings. A bin may denote a binary value of onedigit. For example, “0” and “1” may each be referred to as a bin. A binstring may denote a binary sequence being configured of bins. Herein,for example, a bin string may be a sequence of consecutive binaryvalues, such as “01”.

According to an embodiment, syntax elements of the intra prediction modeinformation and the corresponding binarization may be as shown below inTable 12.

TABLE 12 Binarization Syntax structure Syntax element Process Inputparameters coding_quadtree( ) qt_split_cu_flag[ ][ ] FL cMax − 1multi_type_tree( ) mtt_split_cu_flag FL cMax = 1mtt_split_cu_vertical_flag FL cMax = 1 mtt_split_cu_binary_flag FL cMax= 1 coding_tree_unit( ) alf_ctb_flag[ ][ ][ ] FL cMax = 1 coding_unit( )cu_skip_flag[ ][ ] FL cMax = 1 pred_mode_flag FL cMax = 1intra_luma_mpm_flag[ ][ ] FL cMax = 1 intra_luma_mpm_idx[ ][ ] TR cMax =5, cRiceParam = 0 intra_luma_mpm_remainder[ ][ ] TB cMax = 60intra_chroma_pred_mode[ ][ ] 9.5.3.6 — merge_affine_flag[ ][ ] FL cMax =1 merge_flag[ ][ ] FL cMax = 1 merge_idx[ ][ ] TR cMax − MaxNumMergeCand− 1, cRiceParam − 0 inter_pred_idc[ x0 ][ y0 ] 9.5.3.7 —inter_affine_flag[ ][ ] FL cMax = 1 cu_affine_type_flag[ ][ ] FL cMax =1 ref_idx_l0[ ][ ] TR cMax − num_ref_idx_l0_active_minus1, cRiceParam =0 mvp_l0_flag[ ][ ] FL cMax = 1 ref_idx TR cMax =num_ref_idx_l1_active_minus1, cRiceParam = 0 mvp_ll_flag[ ][ ] FL cMax −1 amyr_mode[ ][ ] TR cMax = 2, cRiceParam = 0 cu_cbf FL cMax = 1mvd_coding( ) abs_mvd_greater0_flag[ ] FL cMax = 1abs_mvd_greater1_flag[ ] FL cMax − 1 abs_mvd_minus2[ ] EG1 —mvd_sign_flag[ ] FL cMax = 1 transform_unit( ) tu_cbf_luma[ ][ ][ ] FLcMax = 1 tu_cbf_cb[ ][ ][ ] FL cMax = 1 tu_cbf_cr[ ][ ][ ] FL cMax − 1cu_mts_flag[ ][ ] FL cMax = 1 residual_coding( ) transform skip flag[ ][][ ] FL cMax = 1 last_sig_coeff_x_prefix TR cMax = ( log2TrafoSize << 1) − 1, cRiceParam = 0 last_sig_coeff_y_prefix TR cMax − ( log2TrafoSize<< 1 ) − 1, cRiceParam = 0 last_sig_coeff_x_suffix FL cMax − ( 1 << ( (last_sig_coeff_x_prefix >> 1 ) − 1 ) − 1 ) last_sig_coeff_y_suffix FLcMax = ( 1 << ( ( last_sig_coeff_y_prefix >> 1 ) − 1 ) − 1 )coded_sub_block_flag[ ][ ] FL cMax − 1 sig_coeff_flag[ ][ ] FL cMax = 1par_level_flag[ ] FL cMax = 1 rem_abs_gt1_flag[ ] FL cMax = 1rem_abs_gt2_flag[ ] FL cMax = 1 abs_remainder[ ] 9.5.3.8 cIdx, x0, y0,xC, yC, log2TbWidth, log2TbHeight coeff sign flag[ ] FL cMax = 1 mtsidx[ ][ ] FL cMax = 3

Referring to Table 12, which is presented above, an“intra_luma_mpm_flag” syntax element indicating an MPM flag may beencoded/decoded by having a fixed-length (FL) binarization processapplied thereto. An “intra_luma_mpm_idx” syntax element indicating anMPM index may be encoded/decoded by having a truncated rice (TR)binarization process applied thereto. And, an “intra_luma_mpm_remainder”syntax element indicating a remaining mode may be encoded/decoded byhaving a truncated binary (TB) binarization process applied thereto.

According to the embodiment of this specification, as described above,by extending the existing 35 intra prediction modes, 67 intra predictionmodes may be used. In this case, when coding the intra prediction modeinformation, 6 bits may be needed for a syntax element indicating theremaining mode. However, depending upon the coding method (i.e.,binarization method), the number of bits of a syntax element indicatingthe remaining mode may be saved. That is, as shown in Table 12, byperforming truncated binary (TB) binarization processing when coding asyntax element indicating the remaining mode, the number of bits may besaved, and the coding efficiency may be enhanced.

According to an embodiment, a truncated binary (TB) binarization processmay be performed on the syntax element indicating the remaining mode, asshown below in Table 13.

TABLE 13 9.5.3.6 Truncated binary binarization process Inputs to to thisprocess are a request for a truncated binary (TB) binarization and cMax.Outputs of this process is the TB binarization associating each valuesymbolVal with a corresponding bin string. Syntax elements coded astb(v) are truncated binary coded. The range of possible values for thesyntax element is determined first. The range of this syntax element maybe between 0 and cMax, with cMax being greater than or equal to 1.symbolVal which is equal to the value of the syntax element is given bya process specified as follows: n = cMax + 1 if( n > 256 ) { thVal = 1<< 8 th = 8 while( thVal <= n ) { th++ thVal <<= 1 } th−− } else { th =Floor ( Log2( n ) ) so that 2^(k) <= n < 2^(k+1) } val = 1 << th (9−9) b= n − val symbolVal = read_bits( th ) if( symbolVal >= val − b ) {symbolVal <<= 1 symbolVal += read_bits( 1 ) symbolVal −= val − b }

Referring to Table 13, in case a syntax element indicating the remainingmode (intra_luma_mpm_remainder) is inputted, a TB binarized value of thesyntax element (intra_luma_mpm_remainder) may be outputted based ontruncated binary (TB) coding. Firstly, a range of feasible values of thesyntax element (intra_luma_mpm_remainder) may be determined, and therange of this syntax element (intra_luma_mpm_remainder) may be between0˜cMax. Herein, cMax may indicate a maximum value (or highest value)that may be assigned to the syntax element (intra_luma_mpm_remainder),and the maximum value may be greater than or equal to 1. A TB binarizedvalue (TB bin string) for the syntax element (intra_luma_mpm_remainder)value may be derived based on an algorithm shown in Table 13. Forexample, as shown in Table 12, in case of a syntax element indicatingthe remaining mode (intra_luma_mpm_remainder), since cMax is equal to60, this syntax element (intra_luma_mpm_remainder) may be expressed byusing 6 bits. However, in case of performing binarization coding on thevalue of the syntax element indicating the remaining mode(intra_luma_mpm_remainder) based on TB coding, which is an algorithmshown in Table 13, the binarization coding may be performed by using anumber of bits less than 6 bits in accordance with the syntax element(intra_luma_mpm_remainder) value. For example, the syntax elementindicating the remaining mode (intra_luma_mpm_remainder) may be coded byTB coding by variably generating bits from 1 bit to 5 bits in accordancewith the value of the corresponding syntax element.

FIG. 15 is a flowchart broadly illustrating an encoding method that maybe performed by an encoding apparatus according to an embodiment of thisspecification.

The method disclosed in FIG. 15 may be performed by the encodingapparatus (200), which is disclosed in FIG. 2. More specifically, stepsS1500 to S1520 of FIG. 15 may be performed by the predictor (220) andthe intra predictor (222) shown in FIG. 2, and step S1530 of FIG. 15 maybe performed by the entropy encoder (240) shown in FIG. 2. Additionally,the method disclosed in FIG. 15 may include the embodiments, which aredescribed above in this specification. Therefore, detailed descriptionon the content of this specification that overlap with theabove-described embodiments shall be omitted or simplified.

Referring to FIG. 15, the encoding apparatus may configure a MostProbable Mode (MPM) list by deriving MPM candidates for the currentblock based on neighboring blocks located in neighboring (orsurrounding) areas of the current block (S1500).

Herein, the neighboring blocks may include neighboring block A,neighboring block B, neighboring block C, neighboring block D,neighboring block E, neighboring block F, and/or neighboring block G,which are described above in FIG. 11.

According to an embodiment, 2 neighboring blocks may be used whenconfiguring the MPM list. Herein, for example, neighboring block D andneighboring block B may be used. Neighboring block D may represent aleft-side neighboring block located at a lowermost position among theleft-side neighboring block being adjacent to the left side of thecurrent block, and neighboring block B may represent an upper-sideneighboring block located at a rightmost (or far right) position amongthe neighboring blocks being adjacent to the upper side of the currentblock.

The encoding apparatus may derive a first MPM candidate based on a firstneighboring block (neighboring block D), and the encoding apparatus mayderive a second MPM candidate based on a second neighboring block(neighboring block B).

For example, when the first neighboring block is available and intraprediction is applied to the first neighboring block, a first MPMcandidate may be derived as an intra prediction mode of the firstneighboring block. When the first neighboring block is unavailable (ornot available) or intra prediction is not applied to the firstneighboring block, a first MPM candidate may be derived as a planarintra prediction mode.

Additionally, for example, when the second neighboring block isavailable and intra prediction is applied to the second neighboringblock and the second neighboring block is included in a current CTU, asecond MPM candidate may be derived as an intra prediction mode of thesecond neighboring block. When the second neighboring block isunavailable (or not available) or intra prediction is not applied to thesecond neighboring block or the second neighboring block is not includedin the current CTU, a second MPM candidate may be derived as a planarintra prediction mode.

The encoding apparatus may configure an MPM list based on the first MPMcandidate and the second MPM candidate, which are derived as describedabove. At this point, in accordance with the number of candidates in theMPM list, the first MPM candidate and the second MPM candidate andremaining (or remainder) MPM candidates may be derived. As describedabove, the number of candidates included in the MPM list may vary inaccordance with the algorithm. Herein, for example, the number ofcandidates may be equal to 3 candidates, 4 candidates, 5 candidates, 6candidates, and so on. Additionally, as described above, additional MPMcandidates may be derived based on conditions that are determined basedon the first MPM candidate derived from the first neighboring block andthe second MPM candidate derived from the second neighboring block.

For example, the encoding apparatus may determine whether or not thefirst MPM candidate and the second MPM candidate are identical, and theencoding apparatus may determine whether a mode number of the first MPMcandidate or the second MPM candidate is greater than a mode number of aDC mode. At this point, when the first MPM candidate and the second MPMcandidate are not identical, the encoding apparatus may determinewhether the mode numbers of both the first MPM candidate and the secondMPM candidate are greater than the DC mode or whether the mode number ofany one of the two MPM candidates is greater than the DC mode.Additionally, when the mode numbers of both the first MPM candidate andthe second MPM candidate are greater than the DC mode, the encodingapparatus may determine based on a difference between the mode numbersof the first MPM candidate and the second MPM candidate (e.g., whetherthe difference between the mode numbers of the two candidates is equalto 1, whether the difference between the mode numbers of the twocandidates is equal to or greater than 2 or 62, and so on). As describedabove, the encoding apparatus may differently configure the MPM list inaccordance with whether or not the above-described conditions aresatisfied based on the first MPM candidate and the second MPM candidate.For example, an MPM list may include 6 MPM candidates, and 6 MPMcandidates including the first MPM candidate and the second MPMcandidate may be derived based on whether or not the above-describedconditions are satisfied. At this point, the 6 MPM candidates may bemapped corresponding to index values of 0 to 5, and the 6 MPM candidatesmay be indicated within the MPM list based on the index values.Therefore, by signaling the index information, the encoding apparatusmay indicate any one of the MPM candidates within the MPM list.

The above-described process of generating an MPM list by deriving MPMcandidates based on the neighboring blocks of the current block ismerely an example. And, therefore, the MPM list may be configured byusing other various methods while considering coding efficiency.Additionally, various embodiments of configuring the MPM list, which aredescribed in this specification, may be applied to the process ofgenerating an MPM list. Since detailed description of the same hasalready been made with reference to FIG. 12 to FIG. 14 and Table 1 toTable 13, in the present embodiment, the same description will beomitted.

The encoding apparatus may determine an intra prediction mode for thecurrent block (S1510).

According to an embodiment, the encoding apparatus may perform variousintra prediction modes for the current block so as to derive an intraprediction mode having an optimal rate-distortion (RD) cost. And, thederived intra prediction mode may be determined as the intra predictionmode of the current block. At this point, the encoding apparatus mayderive an optimal intra prediction mode for the current block based onintra prediction modes including 2 non-directional intra predictionmodes and 65 directional intra prediction modes. The 67 intra predictionmodes have already been described above in detail with reference to FIG.10.

Moreover, the encoding apparatus may generate information on the intraprediction mode of the current block. As information for indicating anintra prediction mode of the current block, the information on the intraprediction mode may include MPM flag information, MPM index information,remaining mode information, and so on.

According to an embodiment, the encoding apparatus may determine whetheror not the determined intra prediction mode of the current block isincluded in the MPM candidates within the MPM list. And, then, theencoding apparatus may generate MPM flag information based on thedetermined result. For example, in case the intra prediction mode forthe current block is included among the MPM candidates within the MPMlist, the encoding apparatus may set the MPM flag information to 1.Alternatively, in case the intra prediction mode for the current blockis not included among the MPM candidates within the MPM list, theencoding apparatus may set the MPM flag information to 0.

Additionally, in case the intra prediction mode for the current block isincluded among the MPM candidates within the MPM list, the encodingapparatus may generate MPM index information indicating the intraprediction mode for the current block among the MPM candidates. Forexample, in case the MPM list is configured by including 6 MPMcandidates, the MPM index information may be index values within therange of 0˜5.

In case the intra prediction mode for the current block is not includedamong the MPM candidates within the MPM list, the encoding apparatus maygenerate remaining mode information indicating the intra prediction modefor the current block among the remaining (or remainder) intraprediction modes excluding the MPM candidates. For example, as describedabove, in case 67 intra prediction modes are used and an MPM list isconfigured by including 6 MPM candidates, the remaining intra predictionmodes may include 61 modes, which is the number of modes obtained bysubtracting the number of MPM candidates from the total number of intraprediction modes. Therefore, the remaining mode information may beindicated as index values within a range of 0˜60.

The encoding apparatus may generate prediction samples for the currentblock by performing intra prediction based on the determined intraprediction mode for the current block (S1520).

According to an embodiment, the encoding apparatus may derive at leastone neighboring sample among neighboring samples of the current blockbased on the intra prediction mode, and, then, the encoding apparatusmay generate prediction samples based on the at least one neighboringsample. Herein, the neighboring samples may include top-left cornerneighboring samples, top side neighboring samples, and left sideneighboring samples of the current block. For example, when the size ofthe current block is W×H and an x component of a top-left sampleposition of the current block is xN and a y component of the top-leftsample position of the current block is yN, left side neighboringsamples may be p[xN−1][yN] to p[xN−1[ ]2H+yN−1], top-left cornerneighboring samples may be p[xN−1][yN−1], and top side neighboringsamples may be p[xN][yN−1] to p[2 W+xN−1][yN−1].

The encoding apparatus may encode image information includinginformation on an intra prediction mode of the current block (S1530).

That is, the encoding apparatus may generate and encode information onan intra prediction mode including at least one of the above-describedMPM flag information, MPM index information, and remaining modeinformation.

As described above, with the extension of the intra prediction mode to67 modes, a larger number of bits are needed to indicate the remainingmode information. Accordingly, in order to enhance coding efficiency,when encoding the remaining mode information, a Truncated Binary (TB)binarization method may be used.

According to an embodiment, the encoding apparatus may encode theabove-described MPM flag information, MPM index information, andremaining mode information based on a binarization process. At thispoint, the binarization process may be performed based on binarizationtype information, which is predetermined for MPM flag information, MPMindex information, and remaining mode information, and, this is asdescribed above in Table 12. According to Table 12, the remaining modeinformation is predefined as a Truncated Binary (TB) binarization type.

MPM candidates may be derived based on 67 intra prediction modes, whichinclude 2 non-directional intra prediction modes and 65 directionalintra prediction modes, as described above. Therefore, the remainingmode information may represent indication information for an intraprediction mode, which is derived based on remaining (or remainder)intra prediction modes excluding the number of MPM candidates (e.g., 6modes) from the 67 intra prediction modes, by a value of a syntaxelement. For example, a value of a syntax element representing theremaining mode information may be expressed by an index value (e.g.,values from 0 to 60) for indicating 61 intra prediction modes.

According to an embodiment, a value of a syntax element representing theremaining mode information may be derived by performing a TruncatedBinary (TB) binarization process based on an algorithm of Table 13,which is presented above. As described above, the remaining modeinformation is expressed by the value of the syntax element, and, asindicated in Table 12, a maximum range (cMax) of the value of the syntaxelement for the remaining mode information may be equal to 60.Therefore, according to the algorithm of Table 13, in case the value ofthe syntax element representing the remaining mode information issmaller than a specific value that is derived based on the number ofremaining intra prediction modes (i.e., cMax) excluding the number ofMPM candidates, the value of the syntax element representing theremaining mode information may be equal to a value, which is derived byusing a variable number of bits ranging from 1 bit to 5 bits based onthe Truncated Binary (TB) binarization process. Conversely, in anopposite case, the value of the syntax element representing theremaining mode information may be derived as a value equal to a value of6 bits based on the Truncated Binary (TB) binarization process. As shownin Table 13, by applying the Truncated Binary (TB) binarization processfor the remaining mode information, the number of bits may be saved inaccordance with the value of the syntax element.

Additionally, although it is not shown in the drawing, the encodingapparatus may derive residual samples for the current block based onoriginal samples and prediction samples for the current block, and theencoding apparatus may generate information on residual for the currentblock based on the residual samples. Moreover, the encoding apparatusmay encode image information including information on the residual andmay output the encoded result in a bitstream format.

A bitstream may be transmitted to a decoding apparatus through a networkor (digital) storage medium. Herein, a network may include a broadcastnetwork and/or communication network, and so on, and a digital storagemedium may include various types of storage media, such as USB, SD, CD,DVD, Blu-ray, HDD, SSD, and so on.

The above-described process of deriving a residual sample for thecurrent block may be performed by the subtractor (231) of the encodingapparatus (200), which is disclosed in FIG. 2. The process of generatinginformation on residual may be performed by the transformer (232) of theencoding apparatus (200), which is disclosed in FIG. 2. And, the processof encoding image information including the information on the residualmay be performed by the entropy encoder (240) of the encoding apparatus(200), which is disclosed in FIG. 2.

FIG. 16 is a flowchart broadly illustrating a decoding method that maybe performed by a decoding apparatus according to an embodiment of thisspecification.

The method disclosed in FIG. 16 may be performed by the decodingapparatus (300), which is disclosed in FIG. 3. More specifically, stepsS1600 to S1620 of FIG. 16 may be performed by the predictor (330) andthe intra predictor (331) shown in FIG. 3. Step S1630 of FIG. 16 may beperformed by the adder (340), which is disclosed in FIG. 3. And, stepS1610 of FIG. 16 may be performed by the entropy decoder (310) shown inFIG. 3. Additionally, the method disclosed in FIG. 16 may include theembodiments, which are described above in this specification. Therefore,detailed description on the content of this specification that overlapwith the above-described embodiments shall be omitted or simplified.

Referring to FIG. 16, the decoding apparatus may configure a MostProbable Mode (MPM) list by deriving MPM candidates for the currentblock based on neighboring blocks located in neighboring (orsurrounding) areas of the current block (S1600).

Herein, the neighboring blocks may include neighboring block A,neighboring block B, neighboring block C, neighboring block D,neighboring block E, neighboring block F, and/or neighboring block G,which are described above in FIG. 11.

According to an embodiment, 2 neighboring blocks may be used whenconfiguring the MPM list. Herein, for example, neighboring block D andneighboring block B may be used. Neighboring block D may represent aleft-side neighboring block located at a lowermost position among theleft-side neighboring block being adjacent to the left side of thecurrent block, and neighboring block B may represent an upper-sideneighboring block located at a rightmost (or far right) position amongthe neighboring blocks being adjacent to the upper side of the currentblock.

The decoding apparatus may derive a first MPM candidate based on a firstneighboring block (neighboring block D), and the decoding apparatus mayderive a second MPM candidate based on a second neighboring block(neighboring block B).

For example, when the first neighboring block is available and intraprediction is applied to the first neighboring block, a first MPMcandidate may be derived as an intra prediction mode of the firstneighboring block. When the first neighboring block is unavailable (ornot available) or intra prediction is not applied to the firstneighboring block, a first MPM candidate may be derived as a planarintra prediction mode.

Additionally, for example, when the second neighboring block isavailable and intra prediction is applied to the second neighboringblock and the second neighboring block is included in a current CTU, asecond MPM candidate may be derived as an intra prediction mode of thesecond neighboring block. When the second neighboring block isunavailable (or not available) or intra prediction is not applied to thesecond neighboring block or the second neighboring block is not includedin the current CTU, a second MPM candidate may be derived as a planarintra prediction mode.

The decoding apparatus may configure an MPM list based on the first MPMcandidate and the second MPM candidate, which are derived as describedabove. At this point, in accordance with the number of candidates in theMPM list, the first MPM candidate and the second MPM candidate andremaining (or remainder) MPM candidates may be derived. As describedabove, the number of candidates included in the MPM list may vary inaccordance with the algorithm. Herein, for example, the number ofcandidates may be equal to 3 candidates, 4 candidates, 5 candidates, 6candidates, and so on. Additionally, as described above, additional MPMcandidates may be derived based on conditions that are determined basedon the first MPM candidate derived from the first neighboring block andthe second MPM candidate derived from the second neighboring block.

For example, the decoding apparatus may determine whether or not thefirst MPM candidate and the second MPM candidate are identical, and thedecoding apparatus may determine whether a mode number of the first MPMcandidate or the second MPM candidate is greater than a mode number of aDC mode. At this point, when the first MPM candidate and the second MPMcandidate are not identical, the decoding apparatus may determinewhether the mode numbers of both the first MPM candidate and the secondMPM candidate are greater than the DC mode or whether the mode number ofany one of the two MPM candidates is greater than the DC mode.Additionally, when the mode numbers of both the first MPM candidate andthe second MPM candidate are greater than the DC mode, the decodingapparatus may determine based on a difference between the mode numbersof the first MPM candidate and the second MPM candidate (e.g., whetherthe difference between the mode numbers of the two candidates is equalto 1, whether the difference between the mode numbers of the twocandidates is equal to or greater than 2 or 62, and so on). As describedabove, the decoding apparatus may differently configure the MPM list inaccordance with whether or not the above-described conditions aresatisfied based on the first MPM candidate and the second MPM candidate.For example, an MPM list may include 6 MPM candidates, and 6 MPMcandidates including the first MPM candidate and the second MPMcandidate may be derived based on whether or not the above-describedconditions are satisfied. At this point, the 6 MPM candidates may bemapped corresponding to index values of 0 to 5, and the 6 MPM candidatesmay be indicated within the MPM list based on the index values.Therefore, the decoding apparatus may determine which candidate is beingindicated among the MPM candidates within the MPM list based on theindex information, which is signaled by the encoding apparatus.

The above-described process of generating an MPM list by deriving MPMcandidates based on the neighboring blocks of the current block ismerely an example. And, therefore, the MPM list may be configured byusing other various methods while considering coding efficiency.Additionally, various embodiments of configuring the MPM list, which aredescribed in this specification, may be applied to the process ofgenerating an MPM list. Since detailed description of the same hasalready been made with reference to FIG. 12 to FIG. 14 and Table 1 toTable 13, in the present embodiment, the same description will beomitted.

The decoding apparatus may derive an intra prediction mode for thecurrent block based on the MPM list (S1610).

According to an embodiment, the decoding apparatus may obtaininformation on the intra prediction mode for the current block from abitstream. As information for indicating an intra prediction mode of thecurrent block, the information on the intra prediction mode may includeMPM flag information, MPM index information, remaining mode information,and so on.

Firstly, the decoding apparatus may obtain MPM flag informationindicating whether or not an intra prediction mode for the current blockis included, among the MPM candidates within the MPM list. Additionally,the decoding apparatus may obtain MPM index information or remainingmode information based on the MPM flag information.

For example, when the MPM flag information indicates 1, the decodingapparatus may determine that an intra prediction mode for the currentblock is included among the MPM candidates within the MPM list. And, inthis case, the decoding apparatus may obtain MPM index informationindicating the intra prediction mode for the current block among the MPMcandidates. The decoding apparatus may derive the MPM candidate beingindicated by the MPM index information within the MPM list as the intraprediction mode for the current block.

When the MPM flag information indicates 0, the decoding apparatus maydetermine that an intra prediction mode for the current block is notincluded among the MPM candidates within the MPM list. And, in thiscase, he decoding apparatus may obtain remaining mode informationindicating the intra prediction mode for the current block among theremaining intra prediction modes excluding the MPM candidates. Thedecoding apparatus may derive the intra prediction mode being indicatedby the remaining mode information as the intra prediction mode for thecurrent block.

As described above, with the extension of the intra prediction mode to67 modes, a larger number of bits are needed to indicate the remainingmode information. Accordingly, in order to enhance coding efficiency,the remaining mode information may be obtained by being decoded based ona Truncated Binary (TB) binarization method.

According to an embodiment, the decoding apparatus may decode theabove-described MPM flag information, MPM index information, andremaining mode information based on a binarization process. At thispoint, the binarization process may be performed based on binarizationtype information, which is predetermined for MPM flag information, MPMindex information, and remaining mode information, and, this is asdescribed above in Table 12. According to Table 12, the remaining modeinformation is predefined as a Truncated Binary (TB) binarization type.

MPM candidates may be derived based on 67 intra prediction modes, whichinclude 2 non-directional intra prediction modes and 65 directionalintra prediction modes, as described above. Therefore, the remainingmode information may represent indication information for an intraprediction mode, which is derived based on remaining (or remainder)intra prediction modes excluding the number of MPM candidates (e.g., 6modes) from the 67 intra prediction modes, by a value of a syntaxelement. For example, a value of a syntax element representing theremaining mode information may be expressed by an index value (e.g.,values from 0 to 60) for indicating 61 intra prediction modes.

According to an embodiment, a value of a syntax element representing theremaining mode information may be derived by performing a TruncatedBinary (TB) binarization process based on an algorithm of Table 13,which is presented above. As described above, the remaining modeinformation is expressed by the value of the syntax element, and, asindicated in Table 12, a maximum range (cMax) of the value of the syntaxelement for the remaining mode information may be equal to 60.Therefore, according to the algorithm of Table 13, in case the value ofthe syntax element representing the remaining mode information issmaller than a specific value that is derived based on the number ofremaining intra prediction modes (i.e., cMax) excluding the number ofMPM candidates, the value of the syntax element representing theremaining mode information may be equal to a value, which is derived byusing a variable number of bits ranging from 1 bit to 5 bits based onthe Truncated Binary (TB) binarization process. Conversely, in anopposite case, the value of the syntax element representing theremaining mode information may be derived as a value equal to a value of6 bits based on the Truncated Binary (TB) binarization process. As shownin Table 13, by applying the Truncated Binary (TB) binarization processfor the remaining mode information, the number of bits may be saved inaccordance with the syntax element value.

The decoding apparatus may generate prediction samples for the currentblock by performing intra prediction based on the derived intraprediction mode for the current block (S1620).

According to an embodiment, the decoding apparatus may derive at leastone neighboring sample among neighboring samples of the current blockbased on the intra prediction mode, and, then, the decoding apparatusmay generate prediction samples based on the at least one neighboringsample. Herein, the neighboring samples may include top-left cornerneighboring samples, top side neighboring samples, and left sideneighboring samples of the current block. For example, when the size ofthe current block is W×H and, an x component of a top-left sampleposition of the current block is xN and a y component of the top-leftsample position of the current block is yN, left side neighboringsamples may be p[xN−1][yN] to p[xN−1][2H+yN−1], top-left cornerneighboring samples may be p[xN−1][yN−1], and top side neighboringsamples may be p[xN][yN−1] to p[2W+xN−1][yN−1].

The decoding apparatus may generate a reconstructed picture for thecurrent block based on prediction samples (S1630).

According to an embodiment, the decoding apparatus may directly useprediction samples as reconstructed samples in accordance with theprediction mode, or the decoding apparatus may generate reconstructedsamples by adding residual samples to the prediction samples.

In case a residual sample for the current block exists, the decodingapparatus may receive information on residual for the current block. Theinformation on residual may include transform coefficients of theresidual samples. The decoding apparatus may derive residual samples (ora residual sample array) for the current block based on the residualinformation. The decoding apparatus may generate reconstructed samplesbased on the prediction samples and the residual samples, and thedecoding apparatus may derive a reconstructed block or reconstructedpicture based on the reconstructed samples. Thereafter, as describedabove, the decoding apparatus may apply an in-loop filtering procedure,such as a deblocking filtering and/or SAO procedure, to thereconstructed picture in order to enhance subjective/objective imagequality, as needed.

In the aforementioned embodiments, although the methods have beendescribed based on the flowcharts in the form of a series of steps orunits, the embodiments of this specification are not limited to theorder of the steps, and some of the steps may be performed in adifferent order from that of other steps or may be performedsimultaneous to other steps. Furthermore, those skilled in the art willunderstand that the steps shown in the flowchart are not exclusive andthe steps may include additional steps or that one or more steps in theflowchart may be deleted without affecting the scope of rights of thisspecification.

The aforementioned method according to this specification may beimplemented in a software form, and the encoding apparatus and/or thedecoding apparatus according to this specification may be included in anapparatus for performing image processing, for example, TV, a computer,a smartphone, a set-top box or a display device.

In this specification, when embodiments are implemented in a softwareform, the aforementioned method be implemented as a module (process,function, and so on) for performing the aforementioned function. Themodule may be stored in the memory and executed by the processor. Thememory may be placed inside or outside the processor and connected tothe processor by various well-known means. The processor may includeapplication-specific integrated circuits (ASICs), other chipsets, logiccircuits and/or data processing devices. The memory may includeread-only memory (ROM), random access memory (RAM), flash memory, memorycards, storage media and/or other storage devices. That is, theembodiments described in this specification may be implemented andperformed on a processor, a micro-processor, a controller or a chip. Forexample, the function units illustrated in the drawings may beimplemented and performed on a computer, a processor, a micro-processor,a controller or a chip. In this case, information (e.g., information oninstructions) or an algorithm for such implementation may be stored in adigital storage medium.

Furthermore, the decoding apparatus and the encoding apparatus to whichthis specification is applied may be included in a multimediabroadcasting transmission and reception device, a mobile communicationterminal, a home cinema video device, a digital cinema video device, acamera for monitoring, a video dialogue device, a real-timecommunication device such as video communication, a mobile streamingdevice, a storage medium, a camcorder, a video on-demand (VoD) serviceprovision device, an over the top (OTT) video device, an Internetstreaming service provision device, a three-dimensional (3D) videodevice, a virtual reality (VR) device, an augmented reality (AR) device,a video telephony device, transportation means terminal (e.g., a vehicle(including autonomous vehicle) terminal, an aircraft terminal, and avessel terminal), and a medical video device, and may be used to processa video signal or a data signal. For example, the over the top (OTT)video device may include a game console, a Blu-ray player, Internetaccess TV, a home theater system, a smartphone, a tablet PC, and adigital video recorder (DVR).

Furthermore, the processing method to which this specification isapplied may be produced in the form of a program executed by a computer,and may be stored in a computer-readable recording medium. Multimediadata having a data structure according to this specification may also bestored in a computer-readable recording medium. The computer-readablerecording medium includes all types of storage devices in whichcomputer-readable data is stored. The computer-readable recording mediummay include Blu-ray disk (BD), a universal serial bus (USB), a ROM, aPROM, an EPROM, an EEPROM, a RAM, a CD-ROM, a magnetic tape, a floppydisk, and an optical data storage device, for example. Furthermore, thecomputer-readable recording medium includes media implemented in theform of carriers (e.g., transmission through the Internet). Furthermore,a bit stream generated using an encoding method may be stored in acomputer-readable recording medium or may be transmitted over wired andwireless communication networks.

Furthermore, an embodiment of this specification may be implemented as acomputer program product using program code. The program code may beperformed by a computer according to an embodiment of thisspecification. The program code may be stored on a carrier readable by acomputer.

FIG. 17 illustrates an example of a content streaming system to whichembodiments disclosed in this specification may be applied.

Referring to FIG. 17, the content streaming system to which theembodiment(s) of the present specification is applied may largelyinclude an encoding server, a streaming server, a web server, a mediastorage, a user device, and a multimedia input device.

The encoding server compresses content input from multimedia inputdevices such as a smartphone, a camera, a camcorder, and so on, intodigital data to generate a bitstream and transmit the bitstream to thestreaming server. As another example, when the multimedia input devicessuch as smartphones, cameras, camcorders, and so on, directly generate abitstream, the encoding server may be omitted.

The bitstream may be generated by an encoding method or a bitstreamgenerating method to which the embodiment(s) of the presentspecification is applied, and the streaming server may temporarily storethe bitstream in the process of transmitting or receiving the bitstream.

The streaming server transmits the multimedia data to the user devicebased on a user's request through the web server, and the web serverserves as a medium for informing the user of a service. When the userrequests a desired service from the web server, the web server deliversit to a streaming server, and the streaming server transmits multimediadata to the user. In this case, the content streaming system may includea separate control server. In this case, the control server serves tocontrol a command/response between devices in the content streamingsystem.

The streaming server may receive content from a media storage and/or anencoding server. For example, when the content is received from theencoding server, the content may be received in real time. In this case,in order to provide a smooth streaming service, the streaming server maystore the bitstream for a predetermined time.

Examples of the user device may include a mobile phone, a smartphone, alaptop computer, a digital broadcasting terminal, a personal digitalassistant (PDA), a portable multimedia player (PMP), navigation, a slatePC, tablet PCs, ultrabooks, wearable devices (e.g., smartwatches, smartglasses, head mounted displays), digital TVs, desktops computer, digitalsignage, and the like.

Each server in the content streaming system may be operated as adistributed server, in which case data received from each server may bedistributed.

Meanwhile, the decoding apparatus and the encoding apparatus to whichthe embodiment of the present disclosure is applied may be included inthe digital device. The “digital device” includes, for example, alldigital devices capable of performing at least one of transmitting,receiving, processing, and outputting data, contents, services, and thelike. Here, processing the data, the contents, the service, and thelike, by the digital device includes an operation of encoding and/ordecoding the data, the contents, the service, and the like. The digitaldevice transmits/receives data by paring or connecting (hereinafter,referred to as ‘paring’) to another digital device, an external server,and so on, through a wired/wireless network and converts the data asnecessary.

Digital devices may, for example, include both standing devices, such asnetwork TV, Hybrid Broadcast Broadband TV (HBBTV), Smart TV, internetprotocol television (IPTV), personal computer (PC), and so on, andmobile devices or handheld devices, such as Personal Digital Assistant(PDA), Smart Phone, Tablet PC, laptop computer, and so on. In thisspecification, for simplicity and convenience, in FIG. 21, which willhereinafter be described in detail, a digital TV will be illustrated anddescribed as an embodiment of the digital device, and, in FIG. 20, amobile (or handheld) device will be illustrated and described in detailas an embodiment of the digital device.

The “wired/wireless network” described in the present disclosure iscollectively referred to as a communication network that supportsvarious communication standards or protocols for interconnection or/anddata transmission/reception between the digital devices or between thedigital device and the external server. The wired/wireless networks mayinclude both communication networks currently supported or to besupported in the future by the standard and communication protocolstherefor and may be formed by communication standards or protocols forwired communication, such as Radio Frequency Identification (RFID),infrared Data Association (IrDA), Ultra Wideband (UWB), ZigBee, DigitalLiving Network Alliance (DLNA), Wireless LAN (WLAN) (Wi-Fi), Wirelessbroadband (Wibro), World Interoperability for Microwave Access (Wimax),High Speed Downlink Packet Access (HSDPA), Long Term Evolution (LTE), orWi-Fi Direct, for example.

Hereinafter, in the present disclosure, when being just referred to asthe digital device, the digital device may mean the standing device orthe mobile device or mean both the standing device and the mobiledevice.

Further, the digital device as an intelligent device that supports abroadcast receiving function, a computer function or support, and atleast one external input, for example, may support e-mail, web browsing,banking, a game, an application, and so on. Moreover, the digital devicemay include an interface for supporting at least one input or controlmeans (hereinafter, referred to as input means) such as a manual inputdevice, a touch screen, a space remote controller, and so on. Thedigital device may use a standardized universal operating system (OS).For example, the digital device may add, delete, amend, update, and soon, various applications on a universal OS kernel and configure, andconfigure and provide a more user-friendly environment through theaddition, deletion, and amendment of various applications.

The external input described in the present disclosure includes allinput means or digital devices which are connected to an external inputdevice, i.e., the digital device wiredly/wirelessly to transmit/receiverelated data through the wired/wireless connection and process thetransmitted/received data. Here, the external input includes all digitaldevices such as a High Definition Multimedia Interface (HDMI), a gamedevice such as a play station or an X-box, a smartphone, a tablet PC, aprinter device, and a smart TV, for example.

Further, the “server” described in the present disclosure as a meaningincluding all digital devices or systems supplying data to a client[0034], i.e., the digital device is also referred to as a processor. Theserver may include a portal server providing a webpage or a web content,an advertising server providing advertising data, a content serverproviding a content, an SNS server providing a social network service(SNS), a service server or manufacturing server provided by amanufacturer, and the like, for example.

Besides, the “channel” described in the present disclosure which means apath, a means, and the like for transmitting/receiving data and abroadcasting channel may be taken as an example of the “channel”. Here,the broadcasting channel is expressed as a term such as a physicalchannel, a virtual channel, a logical channel, and so on, according toactivation of digital broadcasting. The broadcasting channel may bereferred to as a broadcasting network. As such, the broadcasting channelrefers to a channel for providing a broadcasting content provided by abroadcasting station or accessing the broadcasting content by a receiverand since the broadcasting content which is primarily based on real-timebroadcasting, the broadcasting channel is also referred to as a livechannel. However, in recent years, a medium for broadcasting is furtherdiversified and non-real time broadcasting is also activated in additionto the real-time broadcasting, and as a result, the live channel may bejust appreciated as a term meaning the entirety of the broadcastingchannel including the non-real time broadcasting in some cases inaddition to the real-time broadcasting.

In the present disclosure, in addition to the broadcasting channel, an“arbitrary channel” is further defined in association with the channel.The arbitrary channel may be provided together with a service guide suchas an Electronic Program Guide (EPG) together with the broadcastingchannel and the service guide, a Graphic User Interface (GUI), or anOn-Screen Display OSD) screen may be configured/provided only with thearbitrary channel.

Unlike a broadcasting channel having a channel number pre-promisedbetween a transmitter and a receiver, the arbitrary channel is a channelarbitrarily allocated by the receiver and a channel number which is notbasically duplicated with a channel number for expressing thebroadcasting channel is allocated to the arbitrary channel. For example,when a specific broadcasting channel is tuned, the receiver receives thebroadcasting content and a broadcasting signal for transmittingsignaling information for the broadcasting content through the tunedchannel. Here, the receiver parses channel information from thesignaling information, and configures a channel browser, EPG, and so on,based on the parsed channel information and provides the configuredchannel browser, EPG, and so on, to a user. When the user makes achannel switch request through an input means, the receiver is a schemeto respond to the channel switch request.

As such, since the broadcasting channel is contents pre-promised betweenthe transmitter and the receiver, when the arbitrary channel isallocated duplicatively with the broadcasting channel, a confusion ofthe user is caused or there is a confusion possibility, and as a result,it is preferable not to duplicatively allocate the channel as describedabove. Meanwhile, since there is still a possibility of the confusion ina channel surfing process of the user even though the arbitrary channelnumber is not duplicatively allocated with the broadcasting channel asdescribed above, allocating the arbitrary channel number by consideringthe confusion possibility is required. The reason is that the arbitrarychannel according to the embodiment of the present disclosure may alsobe implemented to be accessed like the broadcasting channel similarly inresponse to the channel switch request of the user through the inputmeans similarly to the conventional broadcasting channel. Accordingly,the arbitrary channel number may be defined and represented as a formwith characters such as arbitrary channel-1, arbitrary channel-2, and soon, rather than a number form like the broadcasting channel forconvenience of an access to the arbitrary channel and convenience ofdistinguishment or identification from the broadcasting channel number.Meanwhile, in this case, even though the representation of the arbitrarychannel number may be the form with the characters such as arbitrarychannel-1, the arbitrary channel number may be recognized andimplemented as the number form such as the number of the broadcastingchannel internally in the receiver. Besides, the arbitrary channelnumber may be provided as the number form like the broadcasting channeland the channel number may be defined and represented by various schemeswhich may be distinguished from the broadcasting channel, such as videocontent channel-1, title-1, video-1, and so on.

The digital device executes a web browser for a web service to providevarious forms of web pages to the user. Here, the web page also includesa web page including a video content and in the embodiment of thepresent disclosure, the video content is separated and processedseparately or independently from the web page. In addition, thearbitrary channel number may be allocated to the separated video contentand the separated video content may be provided through the serviceguide and the user may implement the separated video content to beoutput according to the channel switch request in the service guide or abroadcasting channel viewing process. Besides, even for the service suchas the broadcasting content, the game, the application, and so on, inaddition to the web service, a predetermined content, an image, anaudio, an item, and so on, may be separated and processed independentlyfrom the broadcasting content, the game, or the application itself andthe arbitrary channel number may be allocated for reproduction,processing, and so on, and implemented as described above.

FIG. 18 is a diagram schematically illustrating one example of a servicesystem including a digital device.

The service system including the digital device includes a contentprovider (CP) (1810), a service provider (SP) (1820), a network provider(NP) (1830), and a home network end user (HNED) (customer) (1840). Here,the HNED (1840) is, for example, a client (1800), i.e., the digitaldevice. The content provider (1810) produces and provides variouscontents. As illustrated in FIG. 18, as the content provider (1810), aterrestrial broadcaster, a cable system operator (SO) or multiple systemoperators (SO), a satellite broadcaster, various Internet broadcasters,private content providers (CPs), and so on, may be exemplified.Meanwhile, the content provider (1810) provides various applications,and so on, in addition to the broadcasting content.

The service provider (1820) service-packages the content provided by thecontent provider (1810) and provides the content to the HNED (1840). Forexample, the service provider (1820) of FIG. 18 packages and provides afirst terrestrial broadcast, a second terrestrial broadcast, the cableMSO, a satellite broadcast, various Internet broadcasts, applications,and so on, to the HNED (1840).

The service provider (1820) provides the service to the client (1800) bya uni-cast or multi-cast scheme. Meanwhile, the service provider (1820)may transmit data to multiple pre-registered clients (1800) at once andto this end, the service provider (1820) may use an Internet GroupManagement Protocol (IGMP), and so on.

The content provider (1810) and the service provider (1820) may be thesame or single entity. For example, the content provided by the contentprovider (1810) is service-packaged and provided to the HNED (1840) anda function of the service provider (1820) may be also performedtogether, or vice versa.

The network provider (1830) provides a network for data exchange betweenthe content provider (1810) or/and the service provider (1820) and theclient (1800).

The client (1800) may transmit/receive data by constructing a homenetwork.

Meanwhile, the content provider (1810) or/and the service provider(1820) in the service system may use a conditional access or contentprotection means for protection of the transmitted content. In thiscase, the client (1800) may use a processing means such as a cable card(point of deployment (POD)), downloadable CAS (DCAS), and so on, inresponse to the conditional access or content protection.

Besides, the client (1800) may use an interactive service through thenetwork (or communication network). In this case, the client (1800) maystill perform the function of the content provider and the conventionalservice provider (1820) may receive the function and transmit thereceived function to the client again.

FIG. 19 is a block diagram illustrated for describing one embodiment ofa digital device. Here, FIG. 19 may correspond to the client (1800) ofFIG. 18 and means the digital device.

The digital device (1900) is configured to include a Network Interface(1901), a TCP/IP Manager (1902), a Service Delivery Manager (1903), anSI decoder (1904), a Demux (1905), an Audio Decoder (1906), a VideoDecoder (1907), a Display A/V and OSD Module (1908), a Service ControlManager (1909), a Service Discovery Manager (1910), an SI & Metadata DB(1911), a Metadata Manager (1912), a service manager (1913), a UImanager (1914), and the like.

The network interface (1901) receives or transmits Internet protocol(IP) packets through the network. In other words, the network interface(1901) receives the service, the content, and so on, from the serviceprovider (1820) through the network.

The TCP/IP manager (1902) takes part in delivering IP packets receivedby the digital device (1900) and IP packets transmitted by the digitaldevice (1900), i.e., packets between a source and a destination. Inaddition, the TCP/IP manager (1902) classifies the received packet(s) tocorrespond to an appropriate protocol and outputs the classifiedpacket(s) to the service delivery manager (1905), the service discoverymanager (1910), the service control manager (1909), the metadata manager(1912), and so on. The service delivery manager (1903) is responsiblefor the control of the received service data. For example, the servicedelivery manager (1903) may use an RTP/RTCP when controlling real-timestreaming data. When transmitting the real-time streaming data by usingthe RTP, the service delivery manager (1903) parses the received datapacket according to the RTP and transmits the parsed data packet to theDEMUX (1905) or store the transmitted data packet in the SI & metadatadatabase (1911) according to the control of the service manager (1913).In addition, the service delivery manager (1903) feeds back the networkreception information to a server providing the service by using theRTCP. The DEMUX (1905) demultiplexes the received packet to audio,video, system information (SI) data, and so on, and transmits the audio,video, system information (SI) data, and so on, to the audio/videodecoder (1906/1907) and the SI decoder (1904), respectively.

The SI decoder (1904) decodes service information such as ProgramSpecific Information (PSI), Program and System Information Protocol(PSIP), Digital Video Broadcasting-Service Information (DVB-SI), and soon, for example.

Further, the SI decoder (1904) stores the decoded service information,for example, in the SI & metadata database (1911). The stored serviceinformation may be read and used by the corresponding configuration by arequest of the user, and so on, for example.

The audio/video decoder (1906/1907) decodes each audio data and videodata demultiplexed by the DEMUX (1905). The decoded audio data and videodata are provided to the user through the display (1908).

The application manager may be configured to include the UI manager(1914) and the service manager (1913), for example. The applicationmanager may manage an overall state of the digital device (1900) andprovide a user interface, and manage another manager.

The UI manager (1914) provides the Graphic User Interface (GUI) for theuser by using the On Screen Display (OSD) and receives a key input fromthe user and performs a device operation depending on the input. Forexample, when the UI manager (1914) receives the key input for channelselection from the user, the UI manager (1914) transmits the key inputsignal to the service manager (1913).

The service manager (1913) controls a manager associated with theservice, such as the service delivery manager (1903), the servicediscovery manager (1910), the service control manager (1909), themetadata manager (1912), and so on.

Further, the service manager (1913) creates a channel map and selectsthe channel by using the channel map according to the key input receivedfrom the user interface manager (1914). In addition, the service manager(1913) receives the service information of the channel from the SIdecoder (1904) and sets an audio/video packet identifier (PID) of theselected channel to the DEMUX (1905). The set PID is used for thedemultiplexing process. Accordingly, the DEMUX (1905) filters audiodata, video data, and SI data by using the PID.

The service discovery manager (1910) provides information required forselecting a service provider providing the service. When receiving asignal for the channel selection from the service manager (1913), theservice discovery manager (1910) finds the service by using theinformation.

The service control manager (1909) is responsible for selecting andcontrolling the service. For example, when the user selects a livebroadcasting service such as the conventional broadcasting scheme, theservice control manager (1909) uses the IGMP or RTSP and when the userselects a service such as Video on Demand (VOD), the service controlmanager (1909) performs the selection and the control of the service byusing the RTSP. The RTSP may provide a trick mode for real-timestreaming. Further, the service control manager (1909) may initializeand manage a session through an IMS gateway (1950) by using an IPMultimedia Subsystem (IMS) and a Session Initiation Protocol (SIP). Theprotocols may be an embodiment and another protocol may be usedaccording to an implementation example.

The metadata manager (1912) manages metadata associated with the serviceand stores the metadata in the SI & metadata database (1911).

The SI & metadata database (1911) stores the service information decodedby the SI decoder (1904), metadata managed by the metadata manager(1912), and information required for selecting the service providerprovided by the service discovery manager (1910). Further, the SI &metadata database (1911) may store set-up data for the system, and soon.

The SI & metadata database (1911) may be implemented by using anon-volatile RAM (NVRAM) or a flash memory.

Meanwhile, the IMS gateway (1950) is a gateway that collects functionsrequired for accessing an IMS based IPTV service.

FIG. 20 is a block diagram illustrated for describing another embodimentof a digital device. In particular, FIG. 20 is a block diagram of amobile device as another embodiment of the digital device.

Referring to FIG. 20, the mobile device (2000) may include a wirelesscommunication unit (2010), an audio/video (A/V) input unit (2020), auser input unit (2030), a sensing unit (2040), an output unit (2050), amemory (2060), an interface unit (2070), a control unit (2080), and apower supply unit (2090). The components illustrated in FIG. 20 are notrequired. Therefore, a mobile device having more components therethan orless components therethan may be implemented.

The wireless communication unit (2010) may include one or more moduleswhich enable wireless communication between the mobile device (2000) andthe wireless communication system or between the mobile device and thenetwork at which the mobile device is positioned. For example, thewireless communication unit (2010) may include a broadcast receivingmodule (2011), a mobile communication module (2012), a wireless Internetmodule (2013), a short-range communication module (2014), and apositional information module (2015).

The broadcast receiving module (2011) receives broadcast signals and/orbroadcast related information from an external broadcast managementserver through the broadcasting channel. Here, the broadcasting channelmay include a satellite channel and a terrestrial channel. The broadcastmanagement server may be a server for generating and transmitting thebroadcast signals and/or broadcast related information or a server forreceiving previously generated broadcast signals and/or broadcastrelated information and transmitting the received broadcast signalsand/or broadcast related information to the terminal. The broadcastsignals may include a TV broadcast signal, a radio broadcast signal, anda data broadcast signal and include even a broadcast signal of a type inwhich the data broadcast signal is combined with the TV broadcast signalor the radio broadcast signal.

The broadcast related information may mean information related to thebroadcast channel, a broadcast program, or a broadcast service provider.The broadcast related information may be provided even through a mobilecommunication network. In this case, the broadcast related informationmay be received by the mobile communication module (2012).

The broadcast related information may exist as various forms, e.g., aform such as Electronic Program Guide (EPG) or Electronic Service Guide(ESG).

For example, the broadcast receiving module (2011) may receive a digitalbroadcast signal by using a digital broadcasting system such as ATSC,Digital Video Broadcasting-Terrestrial (DVB-T), DVB-S (satellite), MediaForward Link Only (MediaFLO), DVB-H (handheld), Integrated ServicesDigital Broadcast-Terrestrial (ISDB-T), and so on. Of course, thebroadcast receiving module (2011) may be configured to be suitable forother broadcast systems as well as the digital broadcasting system.

The broadcast signal and/or broadcast related information receivedthrough the broadcast receiving module (2011) may be stored in thememory (2060).

The mobile communication module (2012) transmits/receives at least oneradio signal to at least one of a base station, an external terminal,and a server on a mobile communication network. The radio signal mayinclude various types of data depending on transmitting/receiving avoice signal, a video communication signal, or a text/multimediamessage.

The wireless Internet module (2013) may include a module for wirelessInternet access and may be internally or externally built in the mobiledevice (2000). As the wireless Internet technology, wireless LAN (WLAN)(Wi-Fi), wireless broadband (Wibro), world interoperability formicrowave access (Wimax), high speed downlink packet access (HSDPA), orthe like, may be used.

The short-range communication module (2014) represents a module forshort-range communication. As short-range communication technology,Bluetooth, radio frequency identification (RFID), infrared dataassociation (IrDA), ultra wideband (UWB), ZigBee, RS-232, RS-485, or thelike may be used.

The positional information module (2015) as a module for obtainingpositional information of the mobile device (2000) may include a GlobalPosition System (GPS) module as an example.

The A/V input unit (2020) which is used for inputting an audio signal ora video signal may include a camera (2021) and a microphone (2022). Thecamera (2021) processes an image frame such as a still image or a movingpicture obtained by an image sensor in a video call mode or aphotographing mode. The processed image frame may be displayed on thedisplay unit (2051).

The images frame processed by the camera (2021) may be stored in thememory (2060) or transmitted to the outside through the wirelessconnection unit (2010). Two or more cameras (2021) may be providedaccording to a use environment.

The microphone (2022) receives an external sound signal by a microphonein a call mode or a recording mode, a voice recognition mode, or thelike, and processes the received external sound signal as electricalvoice data. The processed voice data may be converted into atransmittable form and transmitted to a mobile communication basestation through the mobile communication module (2012) in the case ofthe call mode. Various noise removal algorithms may be implemented inthe microphone (2022) to remove noise generated in receiving theexternal sound signal.

The user input unit (2030) generates input data for the user to controlthe operation of the terminal. The user input unit (2030) may include akeypad, a dome switch, a touch pad (resistive/capacitive), a jog wheel,a jog switch, and the like.

The sensing unit (2040) generates a sensing signal for an operationcontrol of the mobile device (2000) by sensing a current state of themobile device (2000), such as an opening/closing state of the mobiledevice (2000), a position of the mobile device (2000), presence of auser contact, an orientation of the mobile device,acceleration/deceleration of the mobile device, and so on. For example,when the mobile device (2000) is moved or inclined, the position or atilt of the mobile device may be sensed. Further, whether the powersupply unit (2090) supplies power, whether the interface unit (2070) iscombined with the external device, and the like may also be sensed.Meanwhile, the sensing unit (2040) may include a proximity sensor (2041)including near field communication (NFC).

The output unit (2050) which is used for generating an output related tosight, hearing, or touch may include a display (2051), a sound outputmodule (2052), an alarm unit (2053), and a haptic module (2054).

The display (2051) displays (outputs) information processed by themobile device (2000). For example, when the mobile device is in the callmode, the display (2051) displays a user interface (UI) or graphic userinterface (GUI) associated with the call. When the mobile device (2000)is in the video call mode or the photographing mode, the display (2051)displays a photographed or/and received image or UI and GUI.

The display (2051) may include at least one of a liquid crystal display(LCD), a thin film transistor-liquid crystal display (TFT LCD), anorganic light-emitting diode (OLED), a flexible display, and a 3Ddisplay.

Some displays among them may be configured as a transparent or lighttransmissive type to view the outside through the displays. This may becalled a transparent display and a representative example of thetransparent display includes a transparent OLED (TOLED), and the like. Arear structure of the display unit (2051) may also be configured as alight transmission structure. By such a structure, the user may see anobject positioned behind a terminal body through a region occupied bythe display unit (2051) of the terminal body.

According to an implementation form of the mobile device (2000), two ormore displays (2051) may exist. For example, in the mobile device(2000), the plurality of displays may be separated from each other orintegrally disposed on one surface, and further, disposed on differentsurfaces, respectively.

When the display (2051) and a sensor (hereinafter, referred to as ‘touchsensor’) form a mutual layer structure (hereinafter, referred to as‘touch screen’), the display (2051) may be used as an input apparatus aswell as the output apparatus. The touch sensor may take the form of, forexample, a touch film, a touch sheet, a touch pad, or the like.

The touch sensor may be configured to convert a change in pressureapplied to a specific portion of the display unit (2051) or capacitancegenerated at the specific portion of the display unit (2051) into anelectrical input signal. The touch sensor may be configured to detecttouch pressure as well as a touched position and area.

When there is a touch input for the touch sensor, a signal(s)corresponding to the touch input is/are sent to a touch controller. Thetouch controller processes the signal(s) and thereafter, transmits datacorresponding thereto to the controller (2080). As a result, thecontroller (2080) may know which region of the display (2051) istouched.

The proximity sensor (2041) may be disposed in an internal area of themobile device covered by the touch screen or near the touch screen. Theproximity sensor refers to a sensor that detects the presence or absenceof an object approaching a predetermined detection surface or an objectwhich exists nearby without mechanical contact using electromagneticfield force or infrared rays. The proximity sensor has a longer lifetimeand higher utilization than the touch sensor.

Examples of the proximity sensor include a transmission typephotoelectric sensor, a direct reflection type photoelectric sensor, amirror reflection type photoelectric sensor, a high frequencyoscillation type proximity sensor, a capacitive proximity sensor, amagnetic proximity sensor, an infrared proximity sensor, and the like.When the touch screen is a capacitive sensor, the touch screen isconfigured to detect the proximity of the pointer by a change of anelectric field depending on the proximity of the pointer. In this case,the touch screen (touch sensor) may be classified as the proximitysensor.

Hereinafter, for easy description, the act of recognizing that thepointer is positioned on the touch screen while the pointer is not incontact with the touch screen is referred to as “proximity touch” andthe act of actually touching the pointer on the screen is referred to as“contact touch”. The position where the pointer is proximately touchedon the touch screen means a position where the pointer is verticallycorresponding to the touch screen when the pointer is touched.

The proximity sensor detects the proximity touch and a proximity touchpattern (e.g., a proximity touch distance, a proximity touch direction,a proximity touch speed, a proximity touch time, a proximity touchposition, a proximity touch movement state, and the like). Informationcorresponding to the sensed proximity touch operation and the proximitytouch pattern may be output on the touch screen.

The sound output module (2052) may output audio data received from thewireless communication unit (2010) or stored in the memory (2060) incall signal receiving, the call mode or a recording mode, a voicerecognition mode, a broadcast receiving mode, and the like. The soundoutput module (2052) may also output a sound signal related to afunction (e.g., a call signal receiving sound, a message receivingsound, or the like) performed by the mobile device (2000). The soundoutput module (2052) may include a receiver, a speaker, a buzzer, andthe like.

The alarm unit (2053) outputs a signal for notifying occurrence of anevent of the mobile device (2000). Examples of the event which occurs inthe mobile device include call signal reception, message reception, keysignal input, touch input, and the like. The alarm unit (2053) may alsooutput another form other than a video signal or an audio signal, forexample, a signal for notifying the occurrence of the event byvibration.

The video signal or the audio signal may be output through the displayunit (2051) or the sound output module (2052) so that the display (2051)and the display (2051) and the sound output module (2052) may beclassified as a part of the alarm unit (2053).

The haptic module (2054) generates various tactile effects that the usermay feel. A typical example of the tactile effect generated by thehaptic module (2054) is vibration. The intensity and pattern of thevibration generated by the tactile module (2054) is controllable. Forexample, different vibrations may be combined and output or sequentiallyoutput.

In addition to the vibration, the haptic module (2054) may varioustactile effects including effects by stimulus including pin arrangementvertically moving with respect to a contact skin surface, spraying forceor suction force of the air through an injection port or a suction port,a touch on the skin surface, contact with an electrode, electrostaticforce, and the like and an effect of reproducing a cold sensation usinga heat absorbing or heatable element.

The haptic module (2054) may be implemented not only to transmit thetactile effect through direct contact but also to allow the user to feelthe tactile effect through the muscles of the finger or arm. At leasttwo haptic modules (2054) may be provided according to a configurationaspect of the mobile device (2000).

The memory (2060) may store a program for a motion of the controller(2080) therein and temporarily store input/output data (e.g., a phonebook, a message, a still image, a moving picture, or the like) therein.The memory (2060) may store data regarding various patterns ofvibrations and sounds output in the touch input on the touch screen.

The memory (2060) may include at least one type of storage medium of aflash memory type storage medium, a hard disk type storage medium, amultimedia card micro type storage medium, a card type memory (forexample, an SD or XD memory, or the like), a random access memory (RAM),a static random access memory (SRAM), a read-only memory (ROM), anelectrically erasable programmable read-only memory (EEPROM), aprogrammable read-only memory (PROM), a magnetic memory, a magneticdisk, and an optical disk. The mobile device (2000) may operate inconnection with a web storage performing a storing function of thememory (2060) on the Internet.

The interface unit (2070) serves as a passage with all external devicesconnected to the mobile device (2000). The interface unit (2070)transmits data from the external device or receives power to deliverpower to each component in the mobile device (2000) or transmits data inthe mobile device (2000) to the external device. For example, awireless/wired headset port, an external charger port, a wired/wirelessdata port, a memory card port, a port connecting a device with anidentification module, an audio input/output (I/O) port, a video I/Oport, an earphone port, and the like may be included in the interfaceunit (2070).

The identification module as a chip for storing various information forauthenticating use rights of the external device (2000) may include auser identification module (UIM), a subscriber identity module (SIM), auniversal subscriber identity module (USIM), and the like. Apparatuses(hereinafter referred to as “identification apparatus”) with theidentification module may be manufactured in a smart card format.Therefore, the identification apparatus may be connected with theterminal (2000) via the port.

The interface unit (2070) may become a passage through which the powerfrom a cradle is supplied to the mobile terminal (2000) when the mobileterminal (2000) is connected to an external cradle or may be a passagethrough which various command signals input from the cradle by the userare delivered to the mobile terminal. The various command signals or thepower input from the cradle may serve as a signal for recognizing thatthe mobile terminal is correctly mounted on the cradle.

The controller (2080) generally controls all operations of the mobiledevice. For example, the controller (2080) performs related control andprocessing for voice call, data communication, video call, and so on.The controller (2080) may include a multimedia module (2081) forreproducing multimedia. The multimedia module (2081) may be implementedin the controller (2080) or implemented apart from the controller(2080). The controller (2080), in particular, the multimedia module(2081) may include the encoding apparatus and/or the decoding apparatus.

The controller (2080) may perform pattern recognition processing torecognize a write input or a drawing input performed on the touch screenas a text or an image.

The power supply unit (2090) receives external power and internal powerby a control of the controller (2080) to supply power required foroperations of respective components.

Various embodiments described herein may be implemented in acomputer-readable recording medium or a recording medium readable by adevice similar to the computer by using, for example, software,hardware, or a combination thereof.

According to hardware implementation, the embodiment described hereinmay be implemented by using at least one of the application specificintegrated circuits (ASICs), the digital signal processors (DSPs), thedigital signal processing devices (DSPDs), the programmable logicdevices (PLDs), the field programmable gate arrays (FPGAs), theprocessors, the controllers, the micro-controllers, the microprocessors,and the electric units for performing other functions. In some cases,the embodiments described in the specification may be implemented by thecontroller (2080) itself.

According to software implementation, embodiments such as a procedureand a function described in the specification may be implemented byseparate software modules. Each of the software modules may perform oneor more functions and operations described in the specification. Asoftware code may be implemented by a software application written by anappropriate program language. Here, the software code may be stored inthe memory (2060) and executed by the controller (2080).

FIG. 21 is a block diagram illustrating another embodiment of a digitaldevice.

Other examples of the digital device (2100) include a broadcastreceiving module (2105), an external device interface module (2135), astorage module (2140), a user input interface module (2150), acontroller (2170), a display (2180), an audio output module (2185), apower supply module (2190) and an image capture module (not shown).Here, the broadcast receiving module (2105) may include at least onetuner (2110), a demodulator (2120), and a network interface module(2130). However, in some cases, the broadcast receiving module (2105)may include the tuner (2110) and the demodulator (2120) but may notinclude the network interface module (2130), or vice versa. In addition,although not shown, the broadcast receiving module (2105) may include amultiplexer to multiplex a signal demodulated by the demodulator (2120)via the tuner (2110) and a signal received through the network interface(2130). In addition, although not shown, the broadcast receiving module(2125) may include a demultiplexer to demultiplex the multiplexed signalor to demultiplex the demodulated signal or a signal passing through thenetwork interface module (2130).

The tuner (2110) receives an RF broadcast signal by tuning a channelselected by a user or all previously stored channels among radiofrequency (RF) broadcast signals received through an antenna. Inaddition, the tuner (2110) converts the received RF broadcast signalinto an intermediate frequency (IF) signal or a baseband signal.

For example, if the received RF broadcast signal is a digital broadcastsignal, the tuner (2110) converts the signal into a digital IF signal(DIF), and if the received RF broadcast signal is an analog broadcastsignal, the tuner (2110) converts the signal into an analog basebandvideo or audio signal (CVBS/SIF). That is, the tuner (2110) may processboth a digital broadcast signal or an analog broadcast signal. Theanalog baseband video or audio signal CVBS/SIF output from the tuner(2110) may be directly input to the controller (2170).

In addition, the tuner (2110) may receive an RF broadcast signal of asingle carrier according to an advanced television system committee(ATSC) scheme or an RF broadcast signal of multiple carriers accordingto a digital video broadcasting (DVB) scheme.

Meanwhile, the tuner (2110) may sequentially tune and receive the RFbroadcast signals of all the stored broadcast channels through a channelmemory function among the RF broadcast signals received through theantenna and convert them into intermediate frequency signals or basebandsignals.

The demodulator (2120) receives and demodulates a digital IF signal DIFconverted by the tuner (2110). For example, when the digital IF signaloutput from the tuner (2110) is an ATSC type, the demodulator (2120)performs 8-Vestigal Side Band (8-VSB) demodulation, for example. Inaddition, the demodulator (2120) may perform channel decoding. To thisend, the demodulator (2120) may include a trellis decoder, ade-interleaver, a Reed-Solomon decoder, and the like to perform trellisdecoding, deinterleaving, and Reed-Solomon decoding.

For example, when the digital IF signal output from the tuner (2110) isa DVB type, the demodulator (2120) performs coded orthogonal frequencydivision modulation (COFDMA) demodulation, for example. In addition, thedemodulator (2120) may perform channel decoding. To this end, thedemodulator (2120) may include a convolution decoder, a deinterleaver, aReed-Solomon decoder, and the like to perform convolutional decoding,deinterleaving, and Reed-Solomon decoding.

The demodulator (2120) may output a stream signal TS after performingdemodulation and channel decoding. In this case, the stream signal maybe a signal multiplexed with an image signal, an audio signal, or a datasignal. For example, the stream signal may be an MPEG-2 transport stream(TS) multiplexed with an MPEG-2 standard image signal, a Dolby AC-3standard audio signal, and the like. Specifically, the MPEG-2 TS mayinclude a header of 4 bytes and a payload of 184 bytes.

Meanwhile, the demodulator (2120) described above may be providedseparately according to the ATSC system and the DVB system. That is, thedigital device may include an ATSC demodulator and a DVB demodulatorseparately.

The stream signal output from the demodulator (2120) may be input to thecontroller (2170). The controller (2170) may control demultiplexing,image/audio signal processing, and the like, and control output of audiothrough the display (2180) and the audio output module (2185).

The external device interface module (2135) provides an environment inwhich various external devices are interfaced to the digital device(2100). To this end, the external device interface module (2135) mayinclude an A/V input/output module (not shown) or a wirelesscommunication module (not shown).

The external device interface module (2135) may be wiredly/wirelesslyconnected to an external device such as a digital versatile disk (DVD),a Blu-ray, a game device, a camera, a camcorder, a computer (laptop,tablet), a smartphone, a Bluetooth device, and a cloud. The externaldevice interface module (2135) transmits an image, audio, or data(including image) signal input from the outside to the controller (2170)of the digital device through the connected external device. Thecontroller (2170) may control the processed video, audio or data signalto be output to the connected external device. To this end, the externaldevice interface module (2135) may further include an A/V input/outputmodule (not shown) or a wireless communication module (not shown).

The A/V input/output module may use a USB terminal, a CVBS (compositevideo banking sync) terminal, a component terminal, an S-video terminal(analog), a DVI digital visual interface (HDMI) terminal, a highdefinition multimedia interface (HDMI) terminal, an RGB terminal, aD-SUB terminal and the like.

The wireless communication module may perform near field communicationwith another electronic device. The digital device (2100) may beconnected to another electronic device via a network according to acommunication protocol such as Bluetooth, radio frequency identification(RFID), infrared data association (IrDA), ultra wideband (UWB), ZigBee,and digital living network alliance (DLNA). It may be networked withother electronic devices according to a communication protocol.

In addition, the external device interface module (2135) may beconnected to various set top boxes through at least one of the variousterminals described above to perform input/output operations with theset top box.

Meanwhile, the external device interface module (2135) may receive anapplication or a list of applications in a neighboring external deviceand transmit the received application or application list to thecontroller (2170) or the storage (2140).

The network interface module (2130) provides an interface for connectingthe digital device (2100) with a wired/wireless network including theinternet. The network interface module (2130) may include, for example,an Ethernet terminal for connection with a wired network, and may use,for example a wireless local area network (WLAN) (Wi-Fi), Wibro(wireless broadband), Wimax (world interoperability for microwaveaccess), and high speed downlink packet access (HSDPA) communicationstandard for connection with a wireless network.

The network interface module (2130) may transmit or receive data withanother user or another digital device through the connected network oranother network linked to the connected network. In particular, thenetwork interface module (2130) may transmit some content data stored inthe digital device (2100) to another user who is registered in advancein the digital device (2100) or a selected user or a selected digitaldevice among other digital devices.

Meanwhile, the network interface module (2130) may access apredetermined web page through a connected network or another networklinked to the connected network. That is, by accessing the predeterminedweb page through the network, the network interface module (2130) maysend or receive data with the server. In addition, the network interfacemodule (2130) may receive content or data provided by a content provideror a network operator. That is, the network interface module (2130) mayreceive content such as a movie, an advertisement, a game, a VOD, abroadcast signal, and related information provided from a contentprovider or a network provider through a network. In addition, thenetwork interface module (2130) may receive the update information andthe update file of firmware provided by the network operator. Inaddition, the network interface module (2130) may transmit data to theInternet or content provider or network operator.

In addition, the network interface module (2130) may selectively receivea desired application from among applications that are open to thepublic through the network.

The storage module (2140) may store a program for processing andcontrolling each signal in the controller (2170), and may store asignal-processed video, audio, or data signal.

In addition, the storage module (2140) may perform a function fortemporarily storing an image, audio, or data signal input from theexternal device interface module (2135) or the network interface module(2130). The storage module (2140) may store information on apredetermined broadcast channel through a channel memory function.

The storage module (2140) may store an application or an applicationlist input from the external device interface module (2135) or thenetwork interface module (2130).

In addition, the storage module (2140) may store various platformsdescribed below.

The storage module (2140) may include at least one type storage mediumamong, for example, a flash memory type, a hard disk type, a multimediacard micro type, a card type memory (e.g., SD or XD memory, and so on),a RAM, or a ROM (EEPROM, and so on). The digital device (2100) mayreproduce and provide a content file (video file, still image file,music file, document file, application file, and so on) stored in thestorage module (2140) to the user.

FIG. 21 illustrates an embodiment in which the storage module (2140) isprovided separately from the controller (2170), but the scope of theembodiments of the present disclosure is not limited thereto. That is,the storage (2140) may be included in the controller (2170).

The user input interface module (2150) transmits a signal input by theuser to the controller (2170) or transmits a signal of the controller(2170) to the user.

For example, the user input interface module (2150) controls poweron/off, channel selection, screen setting, and so on, by a controlsignal received from the remote controller (2195) according to variouscommunication methods such as an RF communication method and an infrared(IR) communication method, or may process and transmit a control signalfrom the controller (2170) to the remote controller (2195).

In addition, the user input interface module (2150) may transmit acontrol signal input from a local key (not shown) such as a power key, achannel key, a volume key, and a set value to the controller (2170).

The user input interface module (2150) may transmit a control signalinput from a sensing module (not shown) that senses a user's gesture tothe controller (2170) or may transmit a signal of the controller (2170)to the sensing module (not shown). Here, the sensing module may includea touch sensor, a voice sensor, a position sensor, an operation sensor,and the like.

The controller (2170) demultiplexes a stream input through the tuner(2110), the demodulator (2120), or the external device interface (2135),or processes a demultiplexed signal to generate and output a signal forvideo or audio output. The controller (2170) may include theabove-described encoding apparatus and/or decoding apparatus.

The image signal processed by the controller (2170) may be input to thedisplay (2180) and displayed as an image corresponding to the imagesignal. In addition, the image signal processed by the controller (2170)may be input to the external output device through the external deviceinterface (2135).

The audio signal processed by the controller (2170) may be output to theaudio output module (2185). In addition, the audio signal processed bythe controller (2170) may be input to the external output device throughthe external device interface (2135).

Although not shown in FIG. 21, the controller (2170) may include ademultiplexer, an image processor, and the like.

The controller (2170) may control overall operations of the digitaldevice (2100). For example, the controller (2170) may control the tuner(2110) to control tuning of an RF broadcast corresponding to a channelselected by a user or a previously stored channel.

The controller (2170) may control the digital device (2100) by a usercommand or an internal program input through the user input interface(2150). In particular, the controller (2170) may access the network sothat the user may download a desired application or application listinto the digital device (2100).

For example, the controller (2170) controls the tuner (2110) to input asignal of a selected channel according to a predetermined channelselection command received through the user input interface (2150). Thecontroller (2170) processes the video, audio or data signal of theselected channel. The controller (2170) allows the channel informationselected by the user to be output through the display (2180) or theaudio output module (2185) together with the processed video or audiosignal.

As another example, the controller (2170) may allow an image signal oraudio signal from an external device, e.g., a camera or a camcorder,input though the external device interface module (2135) to be outputthrough the display (2180) or the audio output module (2185) accordingto an external device image playback command received through the userinput interface (2150).

The controller (2170) may control the display (2180) to display animage. For example, the controller (2170) may control the display (2180)to display a broadcasting image input through the tuner (2110), anexternal input image input through the external device interface module(2135), an image input through a network interface module, or an imagestored in the storage module (2140). In this case, the image displayedon the display (2180) may be a still image or video and may be a 2Dimage or a 3D image.

In addition, the controller (2170) may control to reproduce the content.In this case, the content may be content stored in the digital device(2100), received broadcast content, or external input content input fromthe outside. The content may be at least one of a broadcasting image, anexternal input image, an audio file, a still image, a connected webscreen, and a document file.

Meanwhile, the controller (2170) may control to display an applicationor a list of applications that may be downloaded from the digital device(2100) or from an external network when entering the application viewitem.

The controller (2170) may control to install and run an applicationdownloaded from an external network, along with various user interfaces.In addition, the controller (2170) may control an image related to anapplication to be executed by a user selection to be displayed on thedisplay (2180).

Although not shown in the drawing, a channel browsing processor may befurther provided to generate a thumbnail image corresponding to achannel signal or an external input signal.

The channel browsing processor may receive a stream signal TS outputfrom the demodulator (2120) or a stream signal output from the externaldevice interface (2135), and extract an image from the input streamsignal to generate a thumbnail image.

The generated thumbnail image may be coded as it is or input to thecontroller (2170). In addition, the generated thumbnail image may becoded in a stream form and input to the controller (2170). Thecontroller (2170) may display a thumbnail list including a plurality ofthumbnail images on the display (2180) using the input thumbnail image.Meanwhile, the thumbnail images in the thumbnail list may be updatedsequentially or simultaneously. Accordingly, the user may easilyrecognize the contents of the plurality of broadcast channels.

The display (2180) converts an image signal, a data signal, an OSDsignal processed by the controller (2170) or an image signal, datasignal, and so on, received from the external device interface module(2135) into R, G, and B signals to generate a drive signal.

The display (2180) may be a PDP, an LCD, an OLED, a flexible display, a3D display, or the like.

The display (2180) may be configured as a touch screen and used as aninput device in addition to the output device.

The audio output module (2185) receives a signal processed by thecontroller (2170), for example, a stereo signal, a 3.1 channel signal,or a 5.1 channel signal, and outputs an audio signal. The audio outputmodule (2185) may be implemented as various types of speakers.

Meanwhile, in order to detect a user's gesture, as described above, asensing module (not shown) including at least one of a touch sensor, avoice sensor, a position sensor, and a motion sensor may be furtherprovided in the digital device (2100). A signal detected by the sensingmodule (not shown) may be transmitted to the controller (2170) throughthe user input interface module (2150).

Meanwhile, an image capture module (not shown) for capturing an imagethe user may be further provided. Image information captured by theimage capture module (not shown) may be input to the controller (2170).

The controller (2170) may detect the user's gesture by combining theimage captured by the image capture module (not shown) or the detectedsignal from the sensing module (not shown).

The power supply module (2190) supplies corresponding power throughoutthe digital device (2100).

In particular, the power supply module (2190) may supply power to thecontroller (2170) which may be implemented in the form of asystem-on-chip (SOC), a display (2180) for displaying an image, and anaudio output module (2185) for audio output.

To this end, the power supply module (2190) may include a converter (notshown) for converting AC power into DC power. Meanwhile, for example,when the display (2180) is implemented as a liquid crystal panel havinga plurality of backlight lamps, an inverter (not shown) capable ofperforming PWM operation may be further provided for brightness varyingor dimming.

The remote controller (2195) transmits a user input to the user inputinterface module (2150). To this end, the remote controller (2195) mayuse Bluetooth, Radio Frequency (RF) communication, infrared (IR)communication, Ultra Wideband (UWB), ZigBee (ZigBee) method and thelike.

In addition, the remote controller (2195) may receive an image, an audioor a data signal output from the user input interface module (2150),display it on the remote controller (2195) or output a sound orvibration.

The digital device (2100) may be a digital broadcast receiver capable ofprocessing a fixed or mobile ATSC or DVB digital broadcast signal.

In addition, the illustrated components of the digital device accordingto an embodiment of the present disclosure may be omitted or the digitaldevice may further include some components which are not illustrated asnecessary. Meanwhile, unlike the above, the digital device may notinclude the tuner and the demodulator and may receive and play contentthrough a network interface module or an external device interfacemodule.

FIG. 22 is a block diagram illustrating an embodiment of a specificconfiguration of the controller of FIG. 19 to FIG. 21.

An example of the controller may include a demultiplexer (2210), animage processor (2220), an on-screen display (OSD) generator (2240), amixer (2250), a frame rate converter (FRC) (2255), and a formatter(2260). In addition, although not shown, the controller may furtherinclude a voice processor and a data processor.

The demultiplexer (2210) demultiplexes an input stream. For example, thedemultiplexer (2210) may demultiplex input MPEG-2 TS into video, audio,and data signals. Here, the stream signal input to the demultiplexer(2210) may be a stream signal output from a tuner, a demodulator, or anexternal device interface module.

The image processor (2220) performs image processing of thedemultiplexed image signal. To this end, the image processor (2220) mayinclude an image decoder (2225) and a scaler (2235).

The image decoder (2225) decodes the demultiplexed image signal, and thescaler (2235) scales resolution of the decoded image signal so that thedisplay may output the same.

The image decoder (2225) may support various standards. For example, theimage decoder (2225) performs the function of the MPEG-2 decoder whenthe image signal is coded in the MPEG-2 standard, and the image decoder(2225) performs a function of the corresponding decoder when the imagesignal is coded based on a digital multimedia broadcasting (DMB) scheme,H.26x (e.g., H. 265, H.266, H.267, and so on) or EVC, and so on.

Meanwhile, the image signal decoded by the video processor (2220) isinput to the mixer (2250).

The OSD generator (2240) generates OSD data according to a user input oritself. For example, the OSD generator (2240) generates data fordisplaying various data in the form of a graphic or text on the screenof the display based on a control signal of the user input interface.The generated OSD data includes various data such as a user interfacescreen of a digital device, various menu screens, widgets, icons,viewing rate information, and the like.

The OSD generator (2240) may generate data for displaying broadcastinformation based on subtitles or EPGs of a broadcasting image.

The mixer (2250) mixes the OSD data generated by the OSD generator(2240) and the image signal processed by the image processor andprovides the same to the formatter (2260). Since the decoded imagesignal and the OSD data are mixed, the OSD is overlaid and displayed onthe broadcasting image or the external input image.

The frame rate converter (FRC) (2255) converts a frame rate of an inputimage. For example, the frame rate converter (2255) may convert a framerate of an input 60 Hz image into a frame rate of, for example, 120 Hzor 240 Hz according to an output frequency of the display. As describedabove, there may be various methods of converting the frame rate. Forexample, when converting the frame rate from 60 Hz to 120 Hz, the framerate converter (2255) may insert the same first frame between the firstframe and a second frame or insert a third frame predicted from thefirst frame and the second frame. As another example, when convertingthe frame rate from 60 Hz to 240 Hz, the frame rate converter (2255) mayinsert three more identical or predicted frames between existing frames.Meanwhile, when no separate frame conversion is performed, the framerate converter (2255) may be bypassed.

The formatter (2260) changes the output of the input frame rateconverter (2255) to match an output format of the display. For example,the formatter (2260) may output R, G, B data signals, and the R, G, Bdata signals may be output as low voltage differential signaling (LVDS)or mini-LVDS. In addition, when the output of the input frame rateconverter (2255) is a 3D image signal, the formatter (2260) may supporta 3D service through the display by configuring and outputting the 3Dform according to the output format of the display.

The voice processor (not shown) in the controller may perform voiceprocessing of a demultiplexed audio signal. The voice processor (notshown) may support processing of various audio formats. For example,even when an audio signal is encoded in a format such as MPEG-2, MPEG-4,AAC, HE-AAC, AC-3, BSAC, EVS, and so on, the voice processor may includea decoder corresponding thereto to process the same.

Also, the voice processor (not shown) in the controller may processbase, treble, volume control, and the like.

The data processor (not shown) in the controller may perform dataprocessing of the demultiplexed data signal. For example, even when thedemultiplexed data signal is coded, the data processor may decode thedemultiplexed data signal. Here, the coded data signal may be EPGinformation including broadcast information such as a start time and anend time of a broadcast program broadcast in each channel.

Meanwhile, the above-described digital device is an example according toan embodiment of the present specification, each component may beintegrated, added, or omitted depending on the specifications of thedigital device that is actually implemented. That is, as needed, two ormore components may be combined into one component or one component maybe subpartitioned into two or more components. In addition, the functionperformed in each block is for explaining an embodiment of the presentspecification, the specific operation or device does not limit the scopeof the embodiment of the present specification.

Meanwhile, the digital device may be an image signal processing devicethat performs signal processing of an image stored in the device or aninput image. As another example of the image signal processing device, aset-top box (STB) excluding the display 680 and the audio output module685 shown in FIGS. 2.3-4, the above-described DVD player, a Blu-rayplayer, a game machine, a computer, and the like may be furtherexemplified.

FIG. 23 illustrates an example in which a screen of a digital devicesimultaneously displays a main image and a sub-image according to anembodiment.

According to an embodiment, the digital device may simultaneouslydisplay a main image (2310) and a sub-image (2320) on the screen (2300).The main image (2310) may be called a first image, and the sub-image(2320) may be called a second image. The main image (2310) and thesub-image (2320) may include a video, a still image, an electronicprogram guide (EPG), a graphical user interface (GUI), an on-screendisplay (OSD), and the like, but are not limited thereto. The main image(2310) may refer to an image which is displayed simultaneously with thesub-image (2320) on the screen (2300) of the electronic device and whichis relatively smaller in size than the screen (2300) of the electronicdevice. In FIG. 2.3-6, the main image (2310) is displayed on the topleft of the screen (2300) of the digital device. However, the positionwhere the main image (2310) is displayed is not limited thereto and itmay be displayed at any location within the screen (2300) of the digitaldevice.

The main image (2310) and the sub-image (2320) may be directly orindirectly related to each other. For example, the main image (2310) maybe a streaming video, and the sub-image (2320) may be a GUI thatsequentially displays thumbnails of videos including information similarto the streaming video. As another example, the main image (2310) may bea broadcasting image and the sub-image (2320) may be an EPG. As anotherexample, the main image (2310) may be a broadcasting image, and thesub-image (2320) may be a GUI. Examples of the main image (2310) and thesub-image (2320) are not limited thereto.

In an embodiment, the main image (2310) may be a broadcasting imagereceived through a broadcasting channel and the sub-image (2320) may beinformation related to a broadcasting image received through abroadcasting channel. The information related to the broadcasting imagereceived through the broadcast channel may include, for example, EPGinformation including a comprehensive channel schedule, detailedinformation of a broadcast program, information on a broadcast programreview, and the like, but is not limited thereto.

In another embodiment, the main image (2310) may be a broadcasting imagereceived through a broadcast channel and the sub-image (2320) may be animage generated based on information previously stored in a digitaldevice. An image generated based on information previously stored in adigital device may include, for example, a basic UI (user interface),basic channel information, an image resolution manipulation UI, a sleepreservation UI, and the like of the EPG but is not limited thereto.

In another embodiment, the main image (2310) may be a broadcasting imagereceived through the broadcast channel and the sub-image (2320) may beinformation related to a broadcasting image received through a network.The information related to the broadcasting image received through thenetwork may be, for example, information obtained through a searchengine based on the network. More specifically, for example, informationrelated to a character currently being displayed on the main image(2310) may be obtained through a search engine based on a network.

However, the example is not limited thereto, and the information relatedto the broadcasting image, which is received through the network, may beobtained by using, for example, an artificial intelligence (AI) system.More specifically, for example, an estimated-location in a map of aplace currently being displayed on the main image (2310) may be obtainedusing deep-learning based on a network and the digital device mayreceive information on the estimated location in the map of the placecurrently displayed on the main image (2310) through a network.

The digital device according to an embodiment may receive at least oneof image information of the main image (2310) and image information ofthe sub-image (2320) from the outside. The image information of the mainimage (2310) may include, for example, a broadcasting signal receivedthrough a broadcasting channel, source code information of the mainimage (2310), and IP packet information of the image (2310) receivedthrough the network, but is not limited thereto. Similarly, the imageinformation of the sub-image (2320) may include, for example, abroadcast signal received through the broadcast channel, source codeinformation of the sub-image (2320), and IP packet information of thesub-image (2320) received through the network, but is not limitedthereto. The digital device may decode the image information of the mainimage (2310) or the image information of the sub-image (2320) receivedfrom the outside and use the same. However, in some cases, the digitaldevice may internally store image information of the main video (2310)or image information of the sub-image (2320).

The digital device may display the main image (2310) and the sub-image(2320) on the screen (2300) of the digital device based on the imageinformation of the main image (2310) and the information related to thesub-image (2320).

In an example, the decoding apparatus (300) of the digital device mayinclude a main image decoding apparatus and a sub-image decodingapparatus, and the main image decoding apparatus and the sub-imagedecoding apparatus each decode the image information of the main image(2310) and the image information of the sub-image (2320), respectively.The renderer may include a main image renderer (first renderer) and asub-image renderer (second renderer), and the main image renderer maydisplay the main image (2310) in a first region of the screen (2300) ofthe digital device based on the information decoded by the main imagedecoding apparatus and the sub-image renderer may display the sub-image(2320) in a second region of the screen (2300) of the digital devicebased on the information decoded by the sub-image decoding apparatus.

In another example, the decoding apparatus (300) of the digital devicemay decode the image information of the main image (2310) and the imageinformation of the sub-image (2320). Based on the information decoded bythe decoding apparatus (300), the renderer may process the main image(2310) and the sub-image (2320) together so that they are simultaneouslydisplayed on the screen (2300) of the digital device.

That is, according to this specification, the digital device may providea video service processing method. The image service processing methodmay include receiving image information, decoding a (main) image basedon the image information, rendering or displaying the decoded image in afirst region of the display, and rendering or displaying a sub-image ina second region of the display. In this case, the decoding of the firstimage may follow the decoding procedure of the decoding apparatus (300)according to FIG. 3. For example, as described above, the decoding ofthe first image may include deriving prediction samples for a currentblock based on inter or intra prediction, deriving residual samples forthe current block based on the received residual information (optional),and generating reconstructed samples based on the prediction samplesand/or the residual samples. Additionally, the decoding of the firstimage may include performing an in-loop filtering procedure on thereconstructed picture including the reconstructed samples.

For example, the sub-image may be an electronic program guide (EPG), anon-screen display (OSD), or a graphical user interface (GUI). Forexample, the image information may be received through a broadcastnetwork, and the information on the sub-image may be received throughthe broadcast network. For example, the image information may bereceived through a communication network, and the information on thesub-image may be received through the communication network. Forexample, the image information may be received through a broadcastingnetwork, and the information on the sub-image may be received through acommunication network. For example, the image information may bereceived through a broadcasting network or a communication network, andthe information on the sub-image may be stored in a storage medium inthe digital device.

The image service processing method being performed by theabove-described digital device according to this specification willhereinafter be described in more detail with reference to FIG. 24.

FIG. 24 is a flowchart broadly illustrating an image service processingmethod that may be performed by a digital device according to anembodiment of this specification.

The method disclosed in FIG. 24 may be performed by the digital device,which is disclosed in FIG. 19 to FIG. 22. More specifically, step S2400of FIG. 24 may be performed by a network interface unit, a wirelesscommunication unit, a broadcast receiving unit (or module) of thedigital device. Steps S2400 to S2410 of FIG. 24 may be performed by adecoding apparatus (first decoder) of the digital device. Step S2420 ofFIG. 24 may be performed by a renderer (first renderer) of the digitaldevice. And, step S2430 may be performed by a renderer (second renderer)of the digital device.

Referring to FIG. 24, the digital device may receive image information(S2400).

According to an embodiment, the digital device may receive imageinformation through a broadcast network or a communication network.Alternatively, the digital device may also obtain image informationbeing stored in a storage medium within the digital device.

The digital device may decode a first image based on the imageinformation (S2410).

Herein, the first image is a main image that is displayed on a screen ofthe digital device, as described above. Herein, the first image may bereferred to as a main image. For example, the first image may be astreaming moving picture or a broadcasting image, and so on.

Additionally, the image information may be information related to thefirst image (i.e., main image). For example, the image information mayinclude broadcasting signal received through a broadcasting channel,source code information of the main image, Internet Protocol (IP) packetinformation of the main image being received through a network, and, soon.

When decoding the first image, the digital device may follow the imagedecoding method performed by the decoding apparatus, which is describedabove with reference to FIG. 3 to FIG. 16.

According to an embodiment, the digital device may derive predictionsamples for the current block based on inter or intra prediction, deriveresidual samples for the current block based on received residualinformation (this process may be omitted), and generate reconstructedsamples based on the prediction samples and/or the residual samples.Moreover, the digital device may additionally perform an in-loopfiltering procedure on a reconstructed picture including reconstructedsamples.

Additionally, in case of applying intra prediction for the currentblock, the digital device may decode the first image by applying theabove-described decoding method of FIG. 16.

According to an embodiment, the digital device may obtain at least oneof Most Probable Mode (MPM) flag information, MPM index information, orremaining mode information, which are included in the image information,for the current block that is currently being decoded within the firstimage. Additionally, the digital device may configure an MPM list byderiving MPM candidates for the current block. The digital device mayderive an intra prediction mode of the current block based on at leastone of the MPM flag information, MPM index information, or remainingmode information, and the MPM list. The digital device may generateprediction samples by performing prediction on the current block basedon the intra prediction mode. The digital device may generate areconstructed picture (first image) for the current block based on theprediction samples.

Herein, when deriving an intra prediction mode of the current block, incase the digital device determines that the intra prediction mode forthe current block is not included among the MPM candidates within theMPM list, based on the MPM flag information, the digital device mayderive an intra prediction mode of the current block based on theremaining mode information. Additionally, the digital device may obtainan intra prediction mode that is to be applied to the current block, bycoding based on a Truncated Binary (TB) binarization process for theremaining mode information.

Additionally, when configuring the MPM list, the digital device mayderive a first MPM candidate and a second MPM candidate based on a firstneighboring block and a second neighboring block, which are located inneighboring positions of the current block. Herein, the firstneighboring block may represent a left-side neighboring block located ata lowermost (or bottom) position, among the left-side neighboring blocksbeing adjacent to the left side of the current block. And, the secondneighboring block may represent a top-side neighboring block located ata rightmost (or far right) position, among the neighboring blocks beingadjacent to the top of the current block. Additionally, the digitaldevice may determine whether the first MPM candidate and the second MPMcandidate are identical, and the digital device may also determinewhether the first MPM candidate or the second MPM candidate has agreater mode number than the mode number of a DC intra prediction mode.At this point, when the first MPM candidate and the second MPM candidateare not identical and both the first MPM candidate and the second MPMcandidate have mode numbers that are greater than the mode number of theDC intra prediction mode, the digital device may derive k number of MPMcandidates including the first MPM candidate and the second MPMcandidate based on a difference between the mode numbers of the firstMPM candidate and the second MPM candidate. For example, the number(i.e., k) of MPM candidates may be equal to 3, 4, 5, 6, and so on, andthis number may be variably determined in accordance with the algorithm.

Herein, the k number of MPM candidates may be derived based on 67 intraprediction modes including 2 non-directional intra prediction modes and65 directional intra prediction modes. Additionally, when the MPM flaginformation indicates that the intra prediction mode of the currentblock is not included among the MPM candidates within the MPM list, theintra prediction mode of the current block may be derived based on theremaining mode information. In this case, the remaining mode informationmay be derived based on remaining intra prediction modes that remainafter excluding the MPM candidates (e.g., k number of candidates) fromthe 67 intra prediction modes. The remaining mode information mayindicate a syntax element value by using indication information (e.g.,index information) indicating one intra prediction mode being applied tothe current block among the remaining intra prediction modes.

Herein, the syntax element value indicating the remaining modeinformation may be derived through a Truncated Binary (TB) binarizationprocess based on a number of remaining intra prediction modes excludingthe MPM candidates from the 67 intra prediction modes. For example, incase the MPM list includes 6 MPM candidates, the syntax element valueindicating the remaining mode information may indicate the 61 remainingintra prediction modes, which remain after excluding the 6 MPMcandidates from the 67 intra prediction modes, by using index valuesranging from 0 to 60. In this case, the syntax element value indicatingthe remaining mode information may be binarized as binary values byusing a variable number of bits ranging from 1 bit to 5 bits through theTruncated Binary (TB) binarization process.

The digital device may process the decoded first image so that thedecoded first image can be displayed on a first region on the displayscreen (S2420). According to an embodiment, the digital device (morespecifically a renderer) may render the decoded first image and may,then, display the first image on a specific location (first region) onthe display screen.

The digital device may process a second image so that the second imagecan be displayed on a second region on the display screen (S2430).According to an embodiment, the digital device (more specifically arenderer) may render a second image and may, then, display the secondimage on a specific location (second region) on the display screen.

Herein, the second image may be an image that is different from thefirst image, and the first image and second image may be directly orindirectly inter-related. The first image may be referred to as a mainimage, and the second image may be referred to as a sub-image. Forexample, the second image may be an electronic program guide (EPG), anon-screen display (OSD), or a graphic user interface (GUI).

According to an embodiment, a main image may be a streaming movingpicture, and a sub-image may be a GUI sequentially displaying thumbnailsof moving pictures including similar information as the streaming movingpicture. For example, information on the sub-image may be receivedthrough a communication network. Alternatively, information on thesub-image may be pre-stored in a storage medium within the digitaldevice.

According to another embodiment, a main image may be a broadcastedimage, and a sub-image may be an EPG related to the broadcasted image.For example, image information related to the main image and informationon the sub-image may be received through a broadcast network.Alternatively, the information on the sub-image may be pre-stored in astorage medium within the digital device. Herein, the information on thesub-image may include EPG information including TV program schedule ofall channels, detailed information on broadcast programs, and so on,broadcast program re-play information, and so on.

According to yet another embodiment, a main image may be a broadcastedimage, and a sub-image may be a GUI. Examples of the main image and thesub-image shall not be limited only to this.

According to yet another embodiment, image information may be receivedthrough a broadcast network, information on the sub-image may bepre-stored in a storage medium within the digital device, the main imagemay be a broadcasted image, and the sub-image may be an image beinggenerated based on the information on the sub-image, which is pre-storedin a storage medium within the digital device. The image that isgenerated based on the stored information on the sub-image may include,for example, a basic User Interface (UI) of the EPG, basic channelinformation, image resolution controlling UI, Sleep mode scheduling UI,and so on. And, the examples shall not be limited only to this.

According to yet another embodiment, the main image may be a broadcastedimage being received through a broadcast channel, and the sub-image maybe information related to a broadcasted image that is received through anetwork. For example, information related to a broadcasted image that isreceived through a network may be information that is obtained through asearch engine that is based on the network. More specifically, forexample, the obtained information may be character-related informationbeing displayed on the main image through the search engine that isbased on the network.

According to yet another embodiment, information related to abroadcasted image that is received through a network may be informationthat is obtained by using an Artificial Intelligence (AI) system. Morespecifically, for example, the obtained information may be anestimated-location in map of a place or venue being displayed on themain image by using network-based deep-learning. The digital device mayreceive information on an estimated-location in map of a place or venuebeing displayed on the main image through the network.

According to yet another embodiment, the information on the sub-imagemay include a broadcast signal that is received through a broadcastchannel, source code information of the sub-image, and/or IP packetinformation of the sub-image that is received through the network, andso on.

The digital device may simultaneously display a main image and asub-image on a screen of the digital device, based on image informationof the main image and information on the sub-image.

1.-14. (canceled)
 15. An image decoding method performed by a decodingapparatus, the method comprising: deriving a first intra prediction modebased on a first neighboring block which is located in a left side of acurrent block; deriving a second intra prediction mode based on a secondneighboring block which is located in an upper side of the currentblock; configuring an Most Probable Mode (MPM) list for the currentblock based on the first intra prediction mode and the second intraprediction mode; deriving an intra prediction mode of the current blockbased on the MPM list; generating prediction samples for the currentblock based on the intra prediction mode; and generating a reconstructedpicture for the current block based on the prediction samples, whereinthe MPM list comprises MPM candidates derived based on whether at leastone of the first intra prediction mode or the second intra predictionmode is non-directional intra prediction mode, wherein the MPMcandidates which are derived based on a case that the first intraprediction mode and the second intra prediction mode are both thenon-directional intra prediction mode, comprise: a DC intra predictionmode, a vertical directional intra prediction mode, a horizontaldirectional intra prediction mode, an intra prediction mode of whichmode number is equal to a mode number of the vertical directional intraprediction mode minus 4, and an intra prediction mode of which modenumber is equal to the mode number of the vertical directional intraprediction mode plus 4, or wherein the MPM candidates which are derivedbased on a case that one of the first intra prediction mode and thesecond intra prediction mode is the non-directional intra predictionmode and the other is directional intra prediction mode, comprise: oneof the first intra prediction mode and the second intra prediction mode,an intra prediction mode of which mode number is equal to a maximum modenumber of the first intra prediction mode and the second intraprediction mode minus 1, an intra prediction mode of which mode numberis equal to the maximum mode number plus 1, an intra prediction mode ofwhich mode number is equal to the maximum mode number minus
 2. 16. Themethod of claim 15, wherein the non-directional intra prediction mode isa planar intra prediction mode or a DC intra prediction mode, and thedirectional intra prediction mode is one of 65 angular intra predictionmodes.
 17. The method of claim 15, wherein the first intra predictionmode is derived as an intra prediction mode of the first neighboringblock, based on a case that the first neighboring block is available andan intra prediction is applied to the first neighboring block, and thefirst intra prediction mode is derived as a planar intra predictionmode, based on a case that the first neighboring block is not availableor the intra prediction is not applied to the first neighboring block.18. The method of claim 15, wherein the second intra prediction mode isderived as an intra prediction mode of the second neighboring block,based on a case that the second neighboring block is available, an intraprediction is applied to the second neighboring block, and the secondneighboring block is included in a current CTU, and the second intraprediction mode is derived as a planar intra prediction mode, based on acase that the second neighboring block is not available or the intraprediction is not applied to the second neighboring block or the secondneighboring block is not included in the current CTU.
 19. The method ofclaim 15, wherein the method further comprising: obtaining MPM flaginformation related to whether the intra prediction mode of the currentblock is one of the MPM candidates; and obtaining MPM index informationor remaining mode information, based on the MPM flag information,wherein based on a value of the MPM flag information being 1, the intraprediction mode of the current block is derived based on the MPM indexinformation indicating the intra prediction mode of the current blockamong the MPM candidates included in the MPM list, or wherein based on avalue of the MPM flag information being 0, the intra prediction mode ofthe current block is derived based on the remaining mode informationindicating the intra prediction mode of the current block excluding theMPM candidates among all available intra prediction modes.
 20. Themethod of claim 19, wherein the remaining mode information is derived asa value of a syntax element derived based on a Truncated Binary (TB)binarization process.
 21. The method of claim 15, wherein thedirectional intra prediction mode is one of a horizontal predictionmode, an up-left diagonal prediction mode or a vertical prediction mode.22. An image encoding method performed by an encoding apparatus, themethod comprising: deriving a first intra prediction mode based on afirst neighboring block which is located in a left side of a currentblock; deriving a second intra prediction mode based on a secondneighboring block which is located in an upper side of the currentblock; configuring an Most Probable Mode (MPM) list for the currentblock based on the first intra prediction mode and the second intraprediction mode; determining an intra prediction mode of the currentblock based on the MPM list; generating prediction samples for thecurrent block based on the intra prediction mode; and encoding imageinformation including information on the intra prediction mode, whereinthe MPM list comprises MPM candidates derived based on whether at leastone of the first intra prediction mode or the second intra predictionmode is non-directional intra prediction mode, wherein the MPMcandidates which are derived based on a case that the first intraprediction mode and the second intra prediction mode are both thenon-directional intra prediction mode, comprise: a DC intra predictionmode, a vertical directional intra prediction mode, a horizontaldirectional intra prediction mode, an intra prediction mode of whichmode number is equal to a mode number of the vertical directional intraprediction mode minus 4, and an intra prediction mode of which modenumber is equal to the mode number of the vertical directional intraprediction mode plus 4, or wherein the MPM candidates which are derivedbased on a case that one of the first intra prediction mode and thesecond intra prediction mode is the non-directional intra predictionmode and the other is directional intra prediction mode, comprise: oneof the first intra prediction mode and the second intra prediction mode,an intra prediction mode of which mode number is equal to a maximum modenumber of the first intra prediction mode and the second intraprediction mode minus 1, an intra prediction mode of which mode numberis equal to the maximum mode number plus 1, an intra prediction mode ofwhich mode number is equal to the maximum mode number minus
 2. 23. Themethod of claim 22, wherein the non-directional intra prediction mode isa planar intra prediction mode or a DC intra prediction mode, and thedirectional intra prediction mode is one of 65 angular intra predictionmodes.
 24. The method of claim 22, wherein the first intra predictionmode is derived as an intra prediction mode of the first neighboringblock, based on a case that the first neighboring block is available andan intra prediction is applied to the first neighboring block, and thefirst intra prediction mode is derived as a planar intra predictionmode, based on a case that the first neighboring block is not availableor the intra prediction is not applied to the first neighboring block.25. The method of claim 22, wherein the second intra prediction mode isderived as an intra prediction mode of the second neighboring block,based on a case that the second neighboring block is available, an intraprediction is applied to the second neighboring block, and the secondneighboring block is included in a current CTU, and the second intraprediction mode is derived as a planar intra prediction mode, based on acase that the second neighboring block is not available or the intraprediction is not applied to the second neighboring block or the secondneighboring block is not included in the current CTU.
 26. The method ofclaim 22, wherein the directional intra prediction mode is one of ahorizontal prediction mode, an up-left diagonal prediction mode or avertical prediction mode.
 27. A non-transitory computer-readable storagemedium storing encoded information causing a decoding apparatus toperform an image decoding method, the method comprising: deriving afirst intra prediction mode based on a first neighboring block which islocated in a left side of a current block; deriving a second intraprediction mode based on a second neighboring block which is located inan upper side of the current block; configuring an Most Probable Mode(MPM) list for the current block based on the first intra predictionmode and the second intra prediction mode; deriving an intra predictionmode of the current block based on the MPM list; generating predictionsamples for the current block based on the intra prediction mode; andgenerating a reconstructed picture for the current block based on theprediction samples, wherein the MPM list comprises MPM candidatesderived based on whether at least one of the first intra prediction modeor the second intra prediction mode is non-directional intra predictionmode, wherein the MPM candidates which are derived based on a case thatthe first intra prediction mode and the second intra prediction mode areboth the non-directional intra prediction mode, comprise: a DC intraprediction mode, a vertical directional intra prediction mode, ahorizontal directional intra prediction mode, an intra prediction modeof which mode number is equal to a mode number of the verticaldirectional intra prediction mode minus 4, and an intra prediction modeof which mode number is equal to the mode number of the verticaldirectional intra prediction mode plus 4, or wherein the MPM candidateswhich are derived based on a case that one of the first intra predictionmode and the second intra prediction mode is the non-directional intraprediction mode and the other is directional intra prediction mode,comprise: one of the first intra prediction mode and the second intraprediction mode, an intra prediction mode of which mode number is equalto a maximum mode number of the first intra prediction mode and thesecond intra prediction mode minus 1, an intra prediction mode of whichmode number is equal to the maximum mode number plus 1, an intraprediction mode of which mode number is equal to the maximum mode numberminus 2.